RFR: 8303413: (fs) Ignore polling interval sensitivity modifiers in PollingWatchService [v3]

[Brian Burkhalter]

> Modify `sun.nio.fs.PollingWatchService` to ignore any polling sensitivity modifiers as done by the other `WatchService`s.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8303413: Simplify SensitivityModifier test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12795/files
  - new: https://git.openjdk.org/jdk/pull/12795/files/be2c1b4c..2e9867bd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12795&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12795&range=01-02

  Stats: 41 lines in 1 file changed: 3 ins; 25 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/12795.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12795/head:pull/12795

PR: https://git.openjdk.org/jdk/pull/12795