RFR: 8377710: Test serviceability/sa/TestJhsdbJstackMixed.java encountered Driver timeout

[Yasumasa Suenaga]

After [JDK-8374469](https://bugs.openjdk.org/browse/JDK-8374469), we saw test failure due to timeout on TestJhsdbJstackMixed.java. See JBS for details.

TestJhsdbJstackMixed.java attemps run tests (up to 20 times) until the condition is met. However it takes long time in some case (with `-XX:+UseCompactObjectHeaders` at least).
The condition seems to be for Linux x86 (32 bit), so we can run the test just once and check whether we see exception on stderr.

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Commit messages:
 - 8377710: Test serviceability/sa/TestJhsdbJstackMixed.java encountered Driver timeout

Changes: https://git.openjdk.org/jdk/pull/29689/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29689&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377710
  Stats: 8 lines in 1 file changed: 6 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29689.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29689/head:pull/29689

PR: https://git.openjdk.org/jdk/pull/29689