tests: Fix history patch window

[serathius]

Watch event time can be much delayed compared to requests. This created rare issues where last failed request was incorrectly discarded.

[serathius]

cc @ahrtr @ptabor @geetasg @tjungblu

[tjungblu]

Nice find!

/lgtm (non-binding)

[codecov-commenter]

Codecov Report

Merging #15101 (1257d0d) into main (6315f1c) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #15101      +/-   ##
==========================================
- Coverage   74.67%   74.62%   -0.06%     
==========================================
  Files         415      415              
  Lines       34341    34341              
==========================================
- Hits        25645    25626      -19     
- Misses       7064     7080      +16     
- Partials     1632     1635       +3     

Flag	Coverage Δ
all	74.62% <ø> (-0.06%)	⬇️

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

Impacted Files	Coverage Δ
client/v3/leasing/util.go	91.66% <0.00%> (-6.67%)	⬇️
client/v3/concurrency/session.go	85.10% <0.00%> (-4.26%)	⬇️
client/v3/leasing/txn.go	88.09% <0.00%> (-3.18%)	⬇️
server/proxy/grpcproxy/watch.go	93.64% <0.00%> (-2.90%)	⬇️
client/v3/experimental/recipes/key.go	75.34% <0.00%> (-2.74%)	⬇️
client/v3/experimental/recipes/double_barrier.go	68.83% <0.00%> (-2.60%)	⬇️
server/etcdserver/api/v3rpc/interceptor.go	73.43% <0.00%> (-1.05%)	⬇️
client/v3/retry_interceptor.go	66.36% <0.00%> (-0.90%)	⬇️
client/v3/leasing/kv.go	89.70% <0.00%> (-0.67%)	⬇️
server/etcdserver/v3_server.go	77.83% <0.00%> (-0.35%)	⬇️
... and 10 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[ahrtr]

LGTM