[jdk26u] RFR: 8373362: Http3TestServer should not log an exception stack trace when it is stopping normally

[Vanitha B P]

Clean Backport.

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Commit messages:
 - Backport 54430a87226096725b13f05326d08629420657ca

Changes: https://git.openjdk.org/jdk26u/pull/36/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk26u&pr=36&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373362
  Stats: 23 lines in 2 files changed: 22 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk26u/pull/36.diff
  Fetch: git fetch https://git.openjdk.org/jdk26u.git pull/36/head:pull/36

PR: https://git.openjdk.org/jdk26u/pull/36