Fix unit test and integration test for test_accept_block and SyncChurn

[eval-exec]

What problem does this PR solve?

Fix unit test and integration test on latest develop branch CI.

What is changed and how it works?

What's Changed:

Related changes

• Wait init_load_unverified thread exit before processing block in unit test
• Don't use unwrap on SyncChurn's Sender'
• Wait rpc_client are ready before send rpc request

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code ci-runs-only: [ quick_checks,linters ]

Side effects

• None

Release note

None: Exclude this PR from the release note.

[eval-exec]

make security-audit failed, investigating....

[eval-exec]

cargo deny check --hide-inclusion-graph --show-stats advisories sources
error[deprecated]: this key has been removed, see https://github.com/EmbarkStudios/cargo-deny/pull/611 for migration information
  ┌─ /home/runner/work/ckb/ckb/deny.toml:2:1
  │
2 │ vulnerability = "deny"
  │ ━━━━━━━━━━━━━

error[deprecated]: this key has been removed, see https://github.com/EmbarkStudios/cargo-deny/pull/611 for migration information
  ┌─ /home/runner/work/ckb/ckb/deny.toml:3:1
  │
3 │ unmaintained = "warn"
  │ ━━━━━━━━━━━━

error[deprecated]: this key has been removed, see https://github.com/EmbarkStudios/cargo-deny/pull/611 for migration information
  ┌─ /home/runner/work/ckb/ckb/deny.toml:5:1
  │
5 │ notice = "deny"
  │ ━━━━━━

deny.toml format is outdated, get the new deny.toml by cargo deny init.

[eval-exec]

@quake Request for review and re-added this PR to merge queue.