test(lightwalletd): wait for successful block ingestion in integration tests

[teor2345]

Motivation

lightwalletd can now ingest blocks from Zebra, so we should wait for the first ingestion in the integration tests.

Solution

• wait for the first block to be ingested by lightwalletd
• allow more time for the tests (should be fixed by Zebra takes too much time to respond to getblock RPC method. #3745)

Review

Anyone can review this PR, it doesn't actually block any work.

This PR is based on PR #3707 + main, it will need a manual rebase.

Reviewer Checklist

• Tests for expected behaviour

Follow Up Work

The next integration RPC is:

• getrawmempool JSON-RPC method #3160

[codecov]

Codecov Report

Merging #3824 (9ed45d9) into main (1f176d9) will increase coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3824      +/-   ##
==========================================
+ Coverage   78.82%   78.88%   +0.06%     
==========================================
  Files         292      292              
  Lines       33560    33571      +11     
==========================================
+ Hits        26454    26484      +30     
+ Misses       7106     7087      -19