RFR: 8355203: [macos] AquaButtonUI and AquaRootPaneUI repaint default button unnecessarily [v2]

[Jeremy Wood]

> This removes the constant repainting of the AquaRootPaneUI's default button.
> 
> A long time ago (before Mac OS Yosemite, around 2014) this was needed to match Aqua's native experience. But the default button no longer pulses, so we don't need to repaint ("pulse") the button continually.
> 
> Here's a clip from a YouTube video I found demonstrating the pulsing effect that this PR removes (you may want to turn your volume off):
> 
> https://github.com/user-attachments/assets/496bc003-ccba-4178-81bc-765e96d94316
> 
> This PR includes a test, but this test has never failed. (That is: this PR does not resolve a failing test.) This test would fail if the default button ever looked the same as a non-default button.
> 
> My primary goal here was to remove the AquaButtonUI's AncestorListener, but while we're here we might as well remove the AquaRootPaneUI's timer and other cleanup.
> 
> I tried and failed to rename the `private static final byte _pulsed` constant. (More details [here](https://github.com/openjdk/jdk/commit/89d0689f226b9e883df464e6f3e8c20074970499).) If anyone has suggestions for how to rename that without errors please let me know.

Jeremy Wood has updated the pull request incrementally with one additional commit since the last revision:

  8344697: use `PULSED` again, but add comment for future reference

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/24778/files
  - new: https://git.openjdk.org/jdk/pull/24778/files/b8a0d31d..60021fcc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24778&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24778&range=00-01

  Stats: 10 lines in 2 files changed: 8 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24778.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24778/head:pull/24778

PR: https://git.openjdk.org/jdk/pull/24778