es/indexer: Drop fatal 40X failures on the floor

[akarve]

Importantly, we choose to skip the dead letter queue in select cases where we are unlikely to recover from the error, so as to avoid failing the batch. We found a case where list_object_versions may return an object that will never be readable (e.g. due to a foreign owner).

[kevinemoore]

This looks like a good change to me. Ideally, we'd capture keys that were not indexed in a better place than just the lambda logs. I don't think the DLQ is any better and we'll end up with more correctly indexed files this way so it seems like a clear win.

[codecov-commenter]

Codecov Report

Merging #1804 into master will increase coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1804      +/-   ##
==========================================
+ Coverage   88.52%   88.67%   +0.15%     
==========================================
  Files          62       62              
  Lines        7143     7168      +25     
==========================================
+ Hits         6323     6356      +33     
+ Misses        820      812       -8     

Flag	Coverage Δ
#api-python	86.58% <ø> (ø)
#lambda	92.37% <100.00%> (+0.38%)	⬆️

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

Impacted Files	Coverage Δ
lambdas/es/indexer/index.py	84.83% <100.00%> (+4.15%)	⬆️
lambdas/es/indexer/test/test_index.py	95.41% <100.00%> (+0.27%)	⬆️

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