[Backport 2.x] Fix flaky SearchCancellationIT tests to avoid race condition

[opensearch-trigger-bot]

Backport d248643 from #5656.

[codecov-commenter]

Codecov Report

Merging #5657 (d248643) into 2.x (f8da145) will increase coverage by 0.33%.
The diff coverage is 51.02%.

❗ Current head d248643 differs from pull request most recent head 917c672. Consider uploading reports for the commit 917c672 to get more accurate results

@@             Coverage Diff              @@
##                2.x    #5657      +/-   ##
============================================
+ Coverage     70.59%   70.93%   +0.33%     
+ Complexity    58605    58578      -27     
============================================
  Files          4740     4760      +20     
  Lines        280514   279515     -999     
  Branches      40881    40348     -533     
============================================
+ Hits         198019   198263     +244     
+ Misses        65962    65098     -864     
+ Partials      16533    16154     -379     

Impacted Files	Coverage Δ
...ark/time/NanoTimeVsCurrentTimeMillisBenchmark.java	0.00% <0.00%> (ø)
...nsearch/gradle/precommit/LicenseHeadersTask.groovy	0.00% <ø> (ø)
.../java/org/opensearch/gradle/JdkDownloadPlugin.java	36.26% <0.00%> (-1.10%)	⬇️
...rg/opensearch/gradle/OpenSearchTestBasePlugin.java	6.81% <0.00%> (-0.25%)	⬇️
...ternal/InternalDistributionArchiveCheckPlugin.java	0.00% <0.00%> (ø)
...ternal/InternalDistributionArchiveSetupPlugin.java	0.00% <ø> (ø)
...ensearch/gradle/precommit/FilePermissionsTask.java	78.78% <ø> (ø)
...search/gradle/precommit/ForbiddenPatternsTask.java	88.40% <ø> (ø)
...g/opensearch/gradle/precommit/LoggerUsageTask.java	0.00% <ø> (ø)
...ensearch/gradle/precommit/ThirdPartyAuditTask.java	0.00% <0.00%> (ø)
... and 1028 more

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[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/8605/
• CommitID: 917c672