Shenandoah: jdk/jfr/event/oldobject/TestSanityDefault.java times out for some heap sizes

Steps to reproduce:

time docker run -m 90000m -v /home/ec2-user/path/:/path amazonlinux /bin/sh -c 'cd /path/ws/openjdk/jdk && /path/soft/jtreg/bin/jtreg -jdk:/path/ws/openjdk/jdk/build/linux-x86_64-server-release/images/jdk/ -vmoptions:"-ea -esa -XX:+UseShenandoahGC" /path/ws/openjdk/jdk/test/jdk/jdk/jfr/event/oldobject/TestSanityDefault.java'
Test results: error: 1
Error: Some tests failed or other problems occurred.
Report written to /path/ws/openjdk/jdk/JTreport/html/report.html
Results written to /path/ws/openjdk/jdk/JTwork

real 2m7.349s
user 0m0.024s
sys 0m0.024s

The test is fast if UseShenandoahGC is not passed:
time docker run -m 90000m -v /home/ec2-user/path/:/path amazonlinux /bin/sh -c 'cd /path/ws/openjdk/jdk && /path/soft/jtreg/bin/jtreg -jdk:/path/ws/openjdk/jdk/build/linux-x86_64-server-release/images/jdk/ -vmoptions:"-ea -esa" /path/ws/openjdk/jdk/test/jdk/jdk/jfr/event/oldobject/TestSanityDefault.java'
Test results: passed: 1
Report written to /path/ws/openjdk/jdk/JTreport/html/report.html
Results written to /path/ws/openjdk/jdk/JTwork

real 0m7.225s
user 0m0.039s
sys 0m0.000s

The test is also fast using UseShenandoahGC if the memory limit is set to 10000m:

time docker run -m 10000m -v /home/ec2-user/path/:/path amazonlinux /bin/sh -c 'cd /path/ws/openjdk/jdk && /v/soft/jtreg/bin/jtreg -jdk:/path/ws/openjdk/jdk/build/linux-x86_64-server-release/images/jdk/ -vmoptions:"-ea -esa -XX:+UseShenandoahGC" /path/ws/openjdk/jdk/test/jdk/jdk/jfr/event/oldobject/TestSanityDefault.java'
Test results: passed: 1
Report written to /path/ws/openjdk/jdk/JTreport/html/report.html
Results written to /path/ws/openjdk/jdk/JTwork

real 0m7.149s
user 0m0.012s
sys 0m0.029s