LUCENE-14611: Reduce memory pressure in TestTermInSetQuery.testDuel

[lsh1215]

Description

This reduces avoidable memory pressure in TestTermInSetQuery.testDuel.

The test is checking query equivalence, not query-cache behavior. It still uses the randomized test-framework newSearcher(reader), but disables query caching for this test so repeated equivalence checks do not retain cached doc-id sets across iterations.

For the no-score comparison path, the test now collects matching doc IDs with the existing test-framework FixedBitSetCollector and compares the resulting bit sets. This avoids materializing full sorted TopDocs when only doc-id equality matters.

This is intentionally different from prior range-cap attempts such as #15084 and #15118: it does not reduce randomized input sizes or change the stress shape. Instead, it removes the pressure sources that are outside the behavior this test is meant to validate.

Local investigation

I could not reproduce the OOM on my machine with the original issue command, likely due to local environment differences. To make the failure mode visible locally, I used the same stress shape with the test JVM constrained to a 16m heap.

With the original code, that 16m squeeze reproduced:

java.lang.OutOfMemoryError: Java heap space

Heap dump inspection, jstat, and JFR heap profiling pointed to avoidable pressure from the randomized query cache retaining doc-id sets and from the no-score branch materializing sorted TopDocs.

Verification

Ran with JDK 26.

./gradlew tidy
BUILD SUCCESSFUL

./gradlew :lucene:core:compileTestJava
BUILD SUCCESSFUL

./gradlew :lucene:core:test --tests "org.apache.lucene.search.TestTermInSetQuery.testDuel" -Ptests.filter=@Nightly -Ptests.jvms=1 -Ptests.seed=B03A5F38917C1431 -Ptests.useSecurityManager=false -Ptests.gui=true -Ptests.file.encoding=UTF-8 -Ptests.vectorsize=128 -Ptests.forceintegervectors=true
:lucene:core:test (SUCCESS): 1 test

./gradlew :lucene:core:test --tests "org.apache.lucene.search.TestTermInSetQuery" -Ptests.jvms=1 -Ptests.seed=B03A5F38917C1431 -Ptests.useSecurityManager=false -Ptests.gui=true -Ptests.file.encoding=UTF-8 -Ptests.vectorsize=128 -Ptests.forceintegervectors=true
:lucene:core:test (SUCCESS): 15 tests, 1 skipped

./gradlew :lucene:core:test --tests "org.apache.lucene.search.TestTermInSetQuery.testSkipperOptimizationGapAssumption" -Ptests.asserts=true -Ptests.file.encoding=UTF-8 -Ptests.gui=true -Ptests.jvmargs= -Ptests.jvms=4 -Ptests.seed=A8777D0B61FEFFBE -Ptests.vectorsize=128
:lucene:core:test (SUCCESS): 1 test

I also re-ran the local 16m squeeze with the inner testDuel loop temporarily raised from 100 to 10000; with this fix applied, it completed successfully instead of reaching the Java heap OOM state observed with the original code.

Fixes #14611.