[jdk21u-dev] RFR: 8339538: Wrong timeout computations in DnsClient

[Paul Hohensee]

Backport for parity with Oracle 21.0.8. Low risk, test-only fix.

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Commit messages:
 - Backport 4beb77192f54f27183285400d7cae7528df64e43

Changes: https://git.openjdk.org/jdk21u-dev/pull/1575/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1575&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339538
  Stats: 332 lines in 4 files changed: 280 ins; 8 del; 44 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1575.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1575/head:pull/1575

PR: https://git.openjdk.org/jdk21u-dev/pull/1575