RFR: 8317139: [JVMCI] oop handles clearing message pollutes event log

[Doug Simon]

The message for the event of clearing oop handles after each libjvmci compilation should only be logged at level 2 (i.e. `-XX:JVMCIEventLogLevel=2` or `-XX:JVMCITraceLevel=2`). Otherwise, it crowds out more useful events in hs-err crash logs. For example:

JVMCI Events (20 events):
Event: 0.853 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 94 to 68
Event: 0.853 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 102 to 63
Event: 0.855 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 70 to 69
Event: 0.856 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 71 to 70
Event: 0.861 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 78 to 77
Event: 0.866 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 82 to 81
Event: 0.870 Thread 0x00007fded01824f0 compacted oop handles in JVMCI runtime 0 from 88 to 85
Event: 0.875 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 91 to 90
Event: 0.876 Thread 0x00007fded01824f0 compacted oop handles in JVMCI runtime 0 from 86 to 52
Event: 0.878 Thread 0x00007fde0002d2f0 compacted oop handles in JVMCI runtime 1 from 69 to 65
Event: 0.897 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 101 to 99
Event: 0.897 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 100 to 70
Event: 0.897 Thread 0x00007fdde00037f0 compacted oop handles in JVMCI runtime 3 from 99 to 66
Event: 0.902 Thread 0x00007fde0002e6d0 compacted oop handles in JVMCI runtime 2 from 71 to 70
Event: 0.916 Thread 0x00007fde0002d2f0 compacted oop handles in JVMCI runtime 1 from 78 to 62
Event: 0.916 Thread 0x00007fdde00037f0 compacted oop handles in JVMCI runtime 3 from 81 to 79
Event: 0.919 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 100 to 80
Event: 0.922 Thread 0x00007fde0002d2f0 compacted oop handles in JVMCI runtime 1 from 70 to 69
Event: 0.923 Thread 0x00007fdde0002470 compacted oop handles in JVMCI runtime 4 from 85 to 84
Event: 0.926 Thread 0x00007fded01824f0 compacted oop handles in JVMCI runtime 0 from 77 to 74

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Commit messages:
 - change log level of "compacted oop handles" JVMCI message to 2

Changes: https://git.openjdk.org/jdk/pull/15956/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15956&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8317139
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15956.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15956/head:pull/15956

PR: https://git.openjdk.org/jdk/pull/15956