[stateless_validation] fix: Pending chunk endorsement cache

[staffik]

Issue: #10560

https://near.zulipchat.com/#narrow/stream/407237-pagoda.2Fcore.2Fstateless-validation/topic/StatelessNet.20planning/near/419827117

• add pending_chunk_endorsements cache to ChunkEndorsementTracker
• if we have an error on get_chunk, add endorsements to pending cache
• on on_chunk_completed, process all pending endorsements for chunk hash
  We discussed previously that full chunk may not be needed. But this solution aligns well with the existing design

[wacban]

very nice!

[wacban]

LGTM

[codecov]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (3f1a431) 71.88% compared to head (9d42db3) 71.90%.
Report is 9 commits behind head on master.

Files	Patch %	Lines
.../stateless_validation/chunk_endorsement_tracker.rs	87.23%	4 Missing and 2 partials ⚠️
tools/amend-genesis/src/lib.rs	72.72%	1 Missing and 2 partials ⚠️
...src/stateless_validation/state_witness_producer.rs	92.30%	0 Missing and 2 partials ⚠️
core/primitives/src/validator_signer.rs	60.00%	2 Missing ⚠️
chain/chain/src/chain.rs	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10568      +/-   ##
==========================================
+ Coverage   71.88%   71.90%   +0.02%     
==========================================
  Files         723      724       +1     
  Lines      147034   147133      +99     
  Branches   147034   147133      +99     
==========================================
+ Hits       105689   105803     +114     
+ Misses      36481    36467      -14     
+ Partials     4864     4863       -1     

Flag	Coverage Δ
backward-compatibility	0.08% <0.00%> (-0.01%)	⬇️
db-migration	0.08% <0.00%> (-0.01%)	⬇️
genesis-check	1.25% <0.00%> (-0.01%)	⬇️
integration-tests	36.88% <69.30%> (-0.01%)	⬇️
linux	71.06% <49.76%> (+0.03%)	⬆️
linux-nightly	71.36% <93.48%> (+0.09%)	⬆️
macos	53.23% <43.72%> (-1.80%)	⬇️
pytests	1.46% <0.00%> (-0.01%)	⬇️
sanity-checks	1.26% <0.00%> (-0.01%)	⬇️
unittests	67.87% <62.32%> (-0.01%)	⬇️
upgradability	0.13% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.