fix: Start LLMQContext early to let VerifyDB() check ChainLock sign…

…atures in coinbase (#5752)

## Issue being fixed or feature implemented
Now that we have ChainLock sigs in coinbase `VerifyDB()` have to process
them. It works most of the time because usually we simply read
contributions from quorum db
https://github.com/dashpay/dash/blob/develop/src/llmq/quorums.cpp#L385.
However, sometimes these contributions aren't available so we try to
re-build them
https://github.com/dashpay/dash/blob/develop/src/llmq/quorums.cpp#L388.
But by the time we call `VerifyDB()` bls worker threads aren't started
yet, so we keep pushing jobs into worker's queue but it can't do
anything and it halts everything.

backtrace:
```
  * frame #0: 0x00007fdd85a2873d libc.so.6`syscall at syscall.S:38
    frame #1: 0x0000555c41152921 dashd_testnet`std::__atomic_futex_unsigned_base::_M_futex_wait_until(unsigned int*, unsigned int, bool, std::chrono::duration<long, std::ratio<1l, 1l> >, std::chrono::duration<long, std::ratio<1l, 1000000000l> >) + 225
    frame #2: 0x0000555c40e22bd2 dashd_testnet`CBLSWorker::BuildQuorumVerificationVector(Span<std::shared_ptr<std::vector<CBLSPublicKey, std::allocator<CBLSPublicKey> > > >, bool) at atomic_futex.h:102:36
    frame #3: 0x0000555c40d35567 dashd_testnet`llmq::CQuorumManager::BuildQuorumContributions(std::unique_ptr<llmq::CFinalCommitment, std::default_delete<llmq::CFinalCommitment> > const&, std::shared_ptr<llmq::CQuorum> const&) const at quorums.cpp:419:65
    frame #4: 0x0000555c40d3b9d1 dashd_testnet`llmq::CQuorumManager::BuildQuorumFromCommitment(Consensus::LLMQType, gsl::not_null<CBlockIndex const*>) const at quorums.cpp:388:37
    frame #5: 0x0000555c40d3c415 dashd_testnet`llmq::CQuorumManager::GetQuorum(Consensus::LLMQType, gsl::not_null<CBlockIndex const*>) const at quorums.cpp:588:37
    frame #6: 0x0000555c40d406a9 dashd_testnet`llmq::CQuorumManager::ScanQuorums(Consensus::LLMQType, CBlockIndex const*, unsigned long) const at quorums.cpp:545:64
    frame #7: 0x0000555c40937629 dashd_testnet`llmq::CSigningManager::SelectQuorumForSigning(Consensus::LLMQParams const&, llmq::CQuorumManager const&, uint256 const&, int, int) at signing.cpp:1038:90
    frame #8: 0x0000555c40937d34 dashd_testnet`llmq::CSigningManager::VerifyRecoveredSig(Consensus::LLMQType, llmq::CQuorumManager const&, int, uint256 const&, uint256 const&, CBLSSignature const&, int) at signing.cpp:1061:113
    frame #9: 0x0000555c408e2d43 dashd_testnet`llmq::CChainLocksHandler::VerifyChainLock(llmq::CChainLockSig const&) const at chainlocks.cpp:559:53
    frame #10: 0x0000555c40c8b09e dashd_testnet`CheckCbTxBestChainlock(CBlock const&, CBlockIndex const*, llmq::CChainLocksHandler const&, BlockValidationState&) at cbtx.cpp:368:47
    frame #11: 0x0000555c40cf75db dashd_testnet`ProcessSpecialTxsInBlock(CBlock const&, CBlockIndex const*, CMNHFManager&, llmq::CQuorumBlockProcessor&, llmq::CChainLocksHandler const&, Consensus::Params const&, CCoinsViewCache const&, bool, bool, BlockValidationState&, std::optional<MNListUpdates>&) at specialtxman.cpp:202:60
    frame #12: 0x0000555c40c00a47 dashd_testnet`CChainState::ConnectBlock(CBlock const&, BlockValidationState&, CBlockIndex*, CCoinsViewCache&, bool) at validation.cpp:2179:34
    frame #13: 0x0000555c40c0e593 dashd_testnet`CVerifyDB::VerifyDB(CChainState&, CChainParams const&, CCoinsView&, CEvoDB&, int, int) at validation.cpp:4789:41
    frame #14: 0x0000555c40851627 dashd_testnet`AppInitMain(std::variant<std::nullopt_t, std::reference_wrapper<NodeContext>, std::reference_wrapper<WalletContext>, std::reference_wrapper<CTxMemPool>, std::reference_wrapper<ChainstateManager>, std::reference_wrapper<CBlockPolicyEstimator>, std::reference_wrapper<LLMQContext> > const&, NodeContext&, interfaces::BlockAndHeaderTipInfo*) at init.cpp:2098:50
    frame #15: 0x0000555c4082fe11 dashd_testnet`AppInit(int, char**) at bitcoind.cpp:145:54
    frame #16: 0x0000555c40823c64 dashd_testnet`main at bitcoind.cpp:173:20
    frame #17: 0x00007fdd85934083 libc.so.6`__libc_start_main(main=(dashd_testnet`main at bitcoind.cpp:160:1), argc=3, argv=0x00007ffcb8ca5b88, init=<unavailable>, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007ffcb8ca5b78) at libc-start.c:308:16
    frame #18: 0x0000555c4082f27e dashd_testnet`_start + 46
```

Fixes #5741

## What was done?
Start LLMQContext early. Alternative solution could be moving bls worker
Start/Stop into llmq context ctor/dtor.

## How Has This Been Tested?
I had a node with that issue. This patch fixed it.

## Breaking Changes
Not sure, hopefully none.

## Checklist:
- [x] I have performed a self-review of my own code
- [x] I have commented my code, particularly in hard-to-understand areas
- [ ] I have added or updated relevant unit/integration/functional/e2e
tests
- [ ] I have made corresponding changes to the documentation
- [x] I have assigned this pull request to a milestone _(for repository
code-owners and collaborators only)_

src/init.cpp

@@ -1930,8 +1930,15 @@ bool AppInitMain(const CoreContext& context, NodeContext& node, interfaces::Bloc
                 creditPoolManager.reset(new CCreditPoolManager(*node.evodb));
                 llmq::quorumSnapshotManager.reset();
                 llmq::quorumSnapshotManager.reset(new llmq::CQuorumSnapshotManager(*node.evodb));
+
+                if (node.llmq_ctx) {
+                    node.llmq_ctx->Interrupt();
+                    node.llmq_ctx->Stop();
+                }
                 node.llmq_ctx.reset();
                 node.llmq_ctx.reset(new LLMQContext(chainman.ActiveChainstate(), *node.connman, *node.evodb, *::sporkManager, *node.mempool, node.peerman, false, fReset || fReindexChainState));
+                // Have to start it early to let VerifyDB check ChainLock signatures in coinbase
+                node.llmq_ctx->Start();
 
                 if (fReset) {
                     pblocktree->WriteReindexing(true);
@@ -2298,8 +2305,6 @@ bool AppInitMain(const CoreContext& context, NodeContext& node, interfaces::Bloc
         node.scheduler->scheduleEvery(std::bind(&PeriodicStats, std::ref(*node.args), std::cref(*node.mempool)), std::chrono::seconds{nStatsPeriod});
     }
 
-    node.llmq_ctx->Start();
-
     // ********************************************************* Step 11: import blocks
 
     if (!CheckDiskSpace(GetDataDir())) {