docstore/awsdynamodb: don't panic on in/not-in filter over a key field

[herdiyana256]

toKeyCondition panics in its default case when a filter on the partition or sort key uses an operator it cannot express as a DynamoDB KeyCondition. docstore's own Where() accepts in/not-in on any field, and bestQueryable selects a Query plan using an op-agnostic hasFilter check on the sort key, so a valid user query such as Where("pk", "=", x).Where("sk", "in", vals) reaches that path. Nothing in the package recovers the panic, so it crashes the calling process during pure-Go query planning, before any network I/O.

This returns false from that case instead, routing the filter to the FilterExpression path rather than panicking. Same class as the empty-in-slice fix in #3754, different code path (toKeyCondition vs toInCondition). Added a regression test covering in and not-in on a key field.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.40%. Comparing base (45d204f) to head (17b65a4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3760      +/-   ##
==========================================
+ Coverage   75.37%   75.40%   +0.02%     
==========================================
  Files         104      104              
  Lines       14241    14241              
==========================================
+ Hits        10734    10738       +4     
+ Misses       2770     2766       -4     
  Partials      737      737              

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