RFR: 8340799: Add border inside instruction frame in PassFailJFrame

[Alexey Ivanov]

This changeset unifies borders used inside the `PassFailJFrame` framework and adds missing borders.

I started it in ![21038](https://git.openjdk.org/jdk/pull/21038) for [JDK-8340306](https://bugs.openjdk.org/browse/JDK-8340306). That changeset handled only the instructions.

This changeset add a border around the entire contents of the instruction frame, adds a border to the log area as well as to the failure reason dialog. The result looks more pleasing and consistent.

I chose the gap of 4 because it plays nicely with fractional scales: 4 × 1.25 = 5 — no fractional pixels.

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Commit messages:
 - 8340799: Add border inside instruction frame in PassFailJFrame

Changes: https://git.openjdk.org/jdk/pull/21327/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21327&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340799
  Stats: 47 lines in 1 file changed: 34 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/21327.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21327/head:pull/21327

PR: https://git.openjdk.org/jdk/pull/21327