RFR: 8334580: Deprecate no-arg constructor BasicSliderUI() for removal [v3]

[Prasanta Sadhukhan]

> The no-arg constructor BasicSliderUI() was added under [JDK-8250852](https://bugs.openjdk.org/browse/JDK-8250852) by mistake. This constructor should be deprecated for removal in future release

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Added why

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19819/files
  - new: https://git.openjdk.org/jdk/pull/19819/files/9dd9697b..40312082

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19819&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19819&range=01-02

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/19819.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19819/head:pull/19819

PR: https://git.openjdk.org/jdk/pull/19819