RFR: 8274560: JFR: Add test for OldObjectSample event when using Shenandoah

[Aleksey Shipilev]

Similar to JDK-8248302, we would like to have a test for Shenandoah. Current `jdk/jfr/event/oldobject/TestObjectDescription.java` fails with Shenandoah and should be excluded. 

Additional testing:
 - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, default: still passes
 - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, `-XX:+UseShenandoahGC`: now skipped
 - [x] `jdk/jfr/event/oldobject/TestObjectDescription.java`, `-XX:+UseZGC`: still skipped
 - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, out of box: passes
 - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, `-XX:+UseShenandoahGC`: passes
 - [x] `jdk/jfr/event/oldobject/TestShenandoah.java`, `-XX:+UseZGC`: skipped

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Commit messages:
 - Copyright year
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/5773/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5773&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274560
  Stats: 80 lines in 2 files changed: 79 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5773.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5773/head:pull/5773

PR: https://git.openjdk.java.net/jdk/pull/5773