Occasional OOMEs when running the test suite

### Description

I've seen `OutOfMemoryError`s a few times recently when doing `./gradlew test` or `./gradlew check`. I don't think this is related to my changes, because it's intermittent and I've seen it across different branches. I tried reporting it at https://bugreport.java.com, but I didn't get a response or an issue to track. Maybe someone here has some insight.

```
> Task :lucene:backward-codecs:compileTestJava
An exception has occurred in the compiler (21.0.1). Please file a bug against the Java compiler via the Java bug reporting page (https://bugreport.java.com) after checking the Bug Database (https://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
java.lang.OutOfMemoryError: GC overhead limit exceeded
at jdk.compiler/com.sun.tools.javac.comp.Check$$Lambda/0x0000009002630470.get(Unknown Source)
at java.base/java.util.stream.Collectors.lambda$groupingBy$52(Collectors.java:1106)
at java.base/java.util.stream.Collectors$$Lambda/0x00000090016e4328.apply(Unknown Source)
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1228)
at java.base/java.util.stream.Collectors.lambda$groupingBy$53(Collectors.java:1106)
at java.base/java.util.stream.Collectors$$Lambda/0x00000090016d8c28.accept(Unknown Source)
at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1939)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
at jdk.compiler/com.sun.tools.javac.comp.Check.methodsGroupedByName(Check.java:2879)
at jdk.compiler/com.sun.tools.javac.comp.Check.checkPotentiallyAmbiguousOverloads(Check.java:2754)
at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:5628)
at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:5543)
at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:5367)
at jdk.compiler/com.sun.tools.javac.comp.Attr.attrib(Attr.java:5306)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1359)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:976)
at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.lambda$doCall$0(JavacTaskImpl.java:104)
at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl$$Lambda/0x0000009001a5e478.call(Unknown Source)
at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.invocationHelper(JavacTaskImpl.java:152)
at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:100)
at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:94)
at org.gradle.internal.compiler.java.IncrementalCompileTask.call(IncrementalCompileTask.java:92)
at org.gradle.api.internal.tasks.compile.AnnotationProcessingCompileTask.call(AnnotationProcessingCompileTask.java:94)
at org.gradle.api.internal.tasks.compile.ResourceCleaningCompilationTask.call(ResourceCleaningCompilationTask.java:57)
at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:55)
```

### Version and environment details

_No response_

Start by reproducing the intermittent failure with ./gradlew test or ./gradlew check, focusing on :lucene:backward-codecs:compileTestJava and the Java compiler stack trace. The issue does not identify a source change or expected fix; work is complete only when the cause and a concrete, verifiable mitigation are established.

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