RFR: 8280889: java/lang/instrument/GetObjectSizeIntrinsicsTest.java fails with -XX:-UseCompressedOops

[Aleksey Shipilev]

Recent test regression after adding new cases in the test. Without compressed oops, ~1G elements `Object[]` array takes >8G of memory, which fails the test. The fix cuts it down to 512M when reference size is 8 bytes. Additionally, `ObjectAlignmentInBytes=32` is excessive for new test configs.

Additional testing: 
 - [x] Linux x86_64 fastdebug, default, affected test still passes
 - [x] Linux x86_32 fastdebug, default, affected test still passes
 - [x] Linux x86_64 fastdebug, `-XX:-UseCompressedOops`, affected test now passes

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Commit messages:
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/7269/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7269&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280889
  Stats: 10 lines in 1 file changed: 1 ins; 3 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7269.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7269/head:pull/7269

PR: https://git.openjdk.java.net/jdk/pull/7269