[jdk16u] RFR: 8260934: java/lang/StringBuilder/HugeCapacity.java fails without Compact Strings

[Aleksey Shipilev]

This stabilizes the test.

Additional testing:
 - [x] Linux x86_64 fastdebug, affected test, `-XX:-CompactStrings`
 - [x] Linux x86_64 fastdebug, affected test, `-XX:+CompactStrings`

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Commit messages:
 - Backport ad54d8dd832b22485d7ac45958cc4c9bfd70fbd2

Changes: https://git.openjdk.java.net/jdk16u/pull/61/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16u&pr=61&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260934
  Stats: 12 lines in 1 file changed: 7 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk16u/pull/61.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16u pull/61/head:pull/61

PR: https://git.openjdk.java.net/jdk16u/pull/61