RFR: 8349058: 'internal proprietary API' warnings make javac warnings unusable [v2]

[Liam Miller-Cushon]

> This change is a partial backout of [JDK-8332744](https://bugs.openjdk.org/browse/JDK-8332744). The logic was reverted, but the test was preserved and updated to reflect the updated behaviour, and some cleanups to benchmark code were kept.
> 
> This restores the ability to use `-XDignore.symbol.file` as an ad-hoc suppression mechanism for `sunapi` diagnostics, see discussion in [JDK-8349058](https://bugs.openjdk.org/browse/JDK-8349058).

Liam Miller-Cushon has updated the pull request incrementally with one additional commit since the last revision:

  Improvements to test

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23448/files
  - new: https://git.openjdk.org/jdk/pull/23448/files/48388688..9bf37fc6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23448&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23448&range=00-01

  Stats: 24 lines in 1 file changed: 17 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/23448.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23448/head:pull/23448

PR: https://git.openjdk.org/jdk/pull/23448