[Consensus] remove Narwhal mode from PR CI (#18010)

## Description 

Sui tests no longer need to run in Narwhal mode per PR. But Narwhal mode
still runs nightly.

Also, remove a few other nightly workflows that are no longer needed.

## Test plan 

CI

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:

.github/workflows/narwhal.yml

@@ -1,15 +1,6 @@
 name: Narwhal
 
 on:
- push:
- branches:
- - 'main'
- - 'devnet'
- - 'testnet'
- - 'mainnet'
- - 'releases/sui-*-release'
- pull_request:
- types: [opened, synchronize, reopened, ready_for_review]
  workflow_dispatch:
  inputs:
  sui_repo_ref:

.github/workflows/rust.yml

@@ -10,6 +10,13 @@ on:
  - 'releases/sui-*-release'
  pull_request:
  types: [opened, synchronize, reopened, ready_for_review]
+ workflow_dispatch:
+ inputs:
+ sui_repo_ref:
+ description: "Branch / commit to test"
+ type: string
+ required: false
+ default: ''
 
 concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}