Bump up test JVM max heap from 2GB to 2.5GB

[abhishekrb19]

A few CI jobs have been consistently failing on master due to OOMs. Specifically, some tests in the Unit & Integration tests CI / unit tests (jdk17, sql-compat=true) / other_modules_test / other modules test (push) are failing -- see error below.

Looking at the heap dump, it appears that there are global references being retained which sort of point to Mockito. One candidate is the use of Mockito spy objects here that somehow have global references and don't get garbage collected. It's not evident yet. The heap dump artifact can be found in any of the recent failed jobs.

In the mean time, increase the JVM size from 2GB to 2.5GB to see if it helps alleviate the ongoing test failures.

Warning:  Tests run: 158, Failures: 0, Errors: 0, Skipped: 6, Time elapsed: 46.51 s -- in org.apache.druid.msq.test.CalciteArraysQueryMSQTest
[INFO] Running org.apache.druid.msq.test.CalciteSelectJoinQueryMSQTest$SortMergeTest
Warning:  Tests run: 586, Failures: 0, Errors: 0, Skipped: 85, Time elapsed: 131.9 s -- in org.apache.druid.msq.test.CalciteSelectJoinQueryMSQTest$SortMergeTest
[INFO] Running org.apache.druid.msq.test.CalciteSelectQueryMSQTest
java.lang.OutOfMemoryError: Java heap space
Dumping heap to /home/runner/work/druid/druid/target/java_pid22365.hprof ...
Heap dump file created [3049991269 bytes in 9.662 secs]
#
# java.lang.OutOfMemoryError: Java heap space
# -XX:OnOutOfMemoryError="chmod 644 /home/runner/work/druid/druid/target/*.hprof"
#   Executing /bin/sh -c "chmod 644 /home/runner/work/druid/druid/target/*.hprof"...
Terminating due to java.lang.OutOfMemoryError: Java heap space

A few failed jobs:

1. https://github.com/apache/druid/actions/runs/10834038415/job/30068115361
2. https://github.com/apache/druid/actions/runs/10824552673/job/30035411027
3. https://github.com/apache/druid/actions/runs/10835792545/job/30073489146

[kgyrtkirk]

I see this as well in some PRs
+1

[kgyrtkirk]

I don't think this is normal;
there are 4503 ObjectMappers in one of the heapdump; and plenty of hashmap-s with ControllerImpl
we have pretty similar issue to this: mockito/mockito#2503