RFR: 8321163: [test] OutputAnalyzer.getExitValue() unnecessarily logs even when process has already completed

[Jaikiran Pai]

Can I please get a review for this change to the test library's `OutputAnalyzer` class, which proposes to remove some unnecessary logging from the `getExitValue()` call?

As noted in https://bugs.openjdk.org/browse/JDK-8321163, right now this method logs:


[2023-11-24T11:47:54.557561Z] Waiting for completion for process 24909
[2023-11-24T11:47:54.557873Z] Waiting for completion finished for process 24909


even when the process has already completed and the exit value already known. The change in this PR makes it such that if the exit value is available then we no longer log this (nor call `process.waitFor()`).

No new tests have been added given the nature of this change. tier1, tier2 and tier3 tests continue to pass with this change.

-------------

Commit messages:
 - 8321163: [test] OutputAnalyzer.getExitValue() unnecessarily logs even when process has already completed

Changes: https://git.openjdk.org/jdk/pull/16919/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16919&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321163
  Stats: 8 lines in 1 file changed: 5 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16919.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16919/head:pull/16919

PR: https://git.openjdk.org/jdk/pull/16919