[lilliput-jdk17u:lilliput] RFR: 8310531: [Lilliput/JDK17] Revert unnecessary test code modifications and fix the tests

[Aleksey Shipilev]

I have walked through the diff against 17u upstream, and reverted the disabled tests that pass with both `+UCOH` and `-UCOH`, and fixes a few others to work with `+UCOH` correctly. This brings us very close to 17u upstream testing-wise.

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Commit messages:
 - Revert ObjectCountEventVerifier.java
 - Fix GetObjectSizeIntrinsicsTest.java for -UCOH / +UCOH
 - Revert runtime/cds/appcds/TestZGCWithCDS.java
 - Revert runtime/cds/appcds/TestCombinedCompressedFlags.java
 - Revert runtime/cds/appcds/CommandLineFlagComboNegative.java
 - Revert runtime/Monitor/SyncOnValueBasedClassTest.java
 - Revert PrintMetaspaceDcmd.java
 - Revert FieldDensityTests.java
 - Revert runtime/CompressedOops/
 - Revert MetaspaceUtilsGtests.java
 - ... and 5 more: https://git.openjdk.org/lilliput-jdk17u/compare/9143eade...dddf566b

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/38/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=38&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310531
  Stats: 225 lines in 16 files changed: 163 ins; 22 del; 40 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/38.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/38/head:pull/38

PR: https://git.openjdk.org/lilliput-jdk17u/pull/38