RFR: 8375480: Remove usage of AppContext from javax/swing/text [v2]

[Phil Race]

> This PR removes usage of AppContext from classes under javax/swing/text.
> Most of the uses were added in specific bug fixes 10-15 years ago but are now obsolete and the tests for those bugs need to be deleted too.

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  8375350

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29259/files
  - new: https://git.openjdk.org/jdk/pull/29259/files/5a03fd34..8e0fde74

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29259&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29259&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29259.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29259/head:pull/29259

PR: https://git.openjdk.org/jdk/pull/29259