RFR: 8298173: GarbageCollectionNotificationContentTest test failed: no decrease in Eden usage

[Kevin Walls]

Test should not check that Eden has decreased in used size if the GCCause is "No GC".

These happen with the message "end of concurrent GC pause" which is logged by the GCMemoryManager _conc_gc_memory_manager (in G1MonitoringSupport).  This GCMemoryManager only interacts with the old gen memory pool, so it is expected that eden usage does not change.

Updated a few variable names to make it more obvious what count and number are recording, and some formatting.  The key  part of the change is at line 137 onwards.

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Commit messages:
 - 8298173: GarbageCollectionNotificationContentTest test failed: no decrease in Eden usage

Changes: https://git.openjdk.org/jdk/pull/11572/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11572&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298173
  Stats: 33 lines in 1 file changed: 8 ins; 4 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/11572.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11572/head:pull/11572

PR: https://git.openjdk.org/jdk/pull/11572