java/lang/ThreadLocal/TestThreadId.java sometimes throws OOME on ppc aix

**Describe the bug**

```
[2021-01-15T18:57:12.127Z] TEST: java/lang/ThreadLocal/TestThreadId.java
[2021-01-15T18:57:12.127Z] TEST JDK: /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image
[2021-01-15T18:57:12.127Z]
[2021-01-15T18:57:12.127Z] ACTION: build -- Passed. Build successful
[2021-01-15T18:57:12.127Z] REASON: Named class compiled on demand
[2021-01-15T18:57:12.127Z] TIME: 0.219 seconds
[2021-01-15T18:57:12.127Z] messages:
[2021-01-15T18:57:12.127Z] command: build TestThreadId
[2021-01-15T18:57:12.127Z] reason: Named class compiled on demand
[2021-01-15T18:57:12.127Z] Test directory:
[2021-01-15T18:57:12.127Z] compile: TestThreadId
[2021-01-15T18:57:12.127Z] elapsed time (seconds): 0.219
[2021-01-15T18:57:12.127Z]
[2021-01-15T18:57:12.127Z] ACTION: compile -- Passed. Compilation successful
[2021-01-15T18:57:12.127Z] REASON: .class file out of date or does not exist
[2021-01-15T18:57:12.127Z] TIME: 0.219 seconds
[2021-01-15T18:57:12.127Z] messages:
[2021-01-15T18:57:12.127Z] command: compile -XDignore.symbol.file=true /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal/TestThreadId.java
[2021-01-15T18:57:12.127Z] reason: .class file out of date or does not exist
[2021-01-15T18:57:12.127Z] Mode: agentvm
[2021-01-15T18:57:12.127Z] Agent id: 1
[2021-01-15T18:57:12.127Z] elapsed time (seconds): 0.219
[2021-01-15T18:57:12.127Z] configuration:
[2021-01-15T18:57:12.127Z] Boot Layer (javac runtime environment)
[2021-01-15T18:57:12.127Z] class path: /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image/lib/tools.jar
[2021-01-15T18:57:12.127Z] /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/jvmtest/openjdk/jtreg/lib/javatest.jar
[2021-01-15T18:57:12.127Z] /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/jvmtest/openjdk/jtreg/lib/jtreg.jar
[2021-01-15T18:57:12.127Z]
[2021-01-15T18:57:12.127Z] javac compilation environment
[2021-01-15T18:57:12.127Z] source path: /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal
[2021-01-15T18:57:12.127Z] class path: /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal
[2021-01-15T18:57:12.127Z] /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal
[2021-01-15T18:57:12.127Z] /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image/lib/tools.jar
[2021-01-15T18:57:12.127Z]
[2021-01-15T18:57:12.127Z] rerun:
[2021-01-15T18:57:12.127Z] cd /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/scratch && \
[2021-01-15T18:57:12.127Z] DISPLAY=:0 \
[2021-01-15T18:57:12.127Z] HOME=/home/jenkins \
[2021-01-15T18:57:12.127Z] LANG=en_US \
[2021-01-15T18:57:12.127Z] PATH=/bin:/usr/bin:/usr/sbin \
[2021-01-15T18:57:12.127Z] TZ=EST5EDT \
[2021-01-15T18:57:12.127Z] /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image/bin/javac \
[2021-01-15T18:57:12.127Z] -J-ea \
[2021-01-15T18:57:12.127Z] -J-esa \
[2021-01-15T18:57:12.127Z] -J-Xmx512m \
[2021-01-15T18:57:12.127Z] -J-XX:+UseCompressedOops \
[2021-01-15T18:57:12.127Z] -J-Dtest.vm.opts='-ea -esa -Xmx512m -XX:+UseCompressedOops' \
[2021-01-15T18:57:12.127Z] -J-Dtest.tool.vm.opts='-J-ea -J-esa -J-Xmx512m -J-XX:+UseCompressedOops' \
[2021-01-15T18:57:12.127Z] -J-Dtest.compiler.opts= \
[2021-01-15T18:57:12.127Z] -J-Dtest.java.opts= \
[2021-01-15T18:57:12.127Z] -J-Dtest.jdk=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image \
[2021-01-15T18:57:12.127Z] -J-Dcompile.jdk=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image \
[2021-01-15T18:57:12.127Z] -J-Dtest.timeout.factor=8.0 \
[2021-01-15T18:57:12.127Z] -J-Dtest.root=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test \
[2021-01-15T18:57:12.127Z] -J-Dtest.name=java/lang/ThreadLocal/TestThreadId.java \
[2021-01-15T18:57:12.127Z] -J-Dtest.file=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal/TestThreadId.java \
[2021-01-15T18:57:12.127Z] -J-Dtest.src=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -J-Dtest.src.path=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -J-Dtest.classes=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -J-Dtest.class.path=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -J-Dtest.class.path.prefix=/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal:/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -d /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -sourcepath /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal \
[2021-01-15T18:57:12.127Z] -classpath /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal:/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/TKG/test_output_16107364376917/jdk_lang_0/work/classes/java/lang/ThreadLocal:/home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdkbinary/j2sdk-image/lib/tools.jar \
[2021-01-15T18:57:12.127Z] -XDignore.symbol.file=true /home/jenkins/workspace/Test_openjdk8_hs_sanity.openjdk_ppc64_aix/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/lang/ThreadLocal/TestThreadId.java
[2021-01-15T18:57:12.127Z]
[2021-01-15T18:57:12.127Z] ACTION: main -- Failed. Execution failed: `main' threw exception: java.lang.OutOfMemoryError: unable to create new native thread
[2021-01-15T18:57:12.127Z] REASON: Assumed action based on file name: run main TestThreadId
[2021-01-15T18:57:12.128Z] TIME: 0.574 seconds
[2021-01-15T18:57:12.128Z] messages:
[2021-01-15T18:57:12.128Z] command: main TestThreadId
[2021-01-15T18:57:12.128Z] reason: Assumed action based on file name: run main TestThreadId
[2021-01-15T18:57:12.128Z] Mode: agentvm
```

**To Reproduce**
Steps to reproduce the behavior (or Grinder rerun link):

https://trss.adoptopenjdk.net/output/test?id=6001f6e92bad7850661329e4

**Expected behavior**
A clear and concise description of what you expected to happen.

No OOME

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Additional context**
Add any other context about the problem here.

Happened 3/12 recent runs

Start with jdk/test/java/lang/ThreadLocal/TestThreadId.java and rerun it using the linked Grinder result on ppc AIX. Investigate the intermittent java.lang.OutOfMemoryError: unable to create new native thread, then verify that repeated runs complete without OOME on the affected platform.

Written by the indexing model from the issue text.