[jdk18u] RFR: 8285956: (fs) Excessive default poll interval in PollingWatchService

[Tyler Steele]

This PR backports changes that reduce the wait time for a user of the WatchService API on AIX and BSD.

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Commit messages:
 - Backport 1bb4de2e2868a539846ec48dd43fd623c2ba69a5
 - Backport fe547eacd71b4eb8119ecc7ca2d0bbe8e757f854

Changes: https://git.openjdk.java.net/jdk18u/pull/121/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=121&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285956
  Stats: 87 lines in 27 files changed: 58 ins; 0 del; 29 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/121.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/121/head:pull/121

PR: https://git.openjdk.java.net/jdk18u/pull/121