RFR: 8346669: Increase abstraction in SetupBuildLauncher and remove extra args

[Magnus Ihse Bursie]

We need to raise the abstraction of the SetupBuildLauncher API, to prepare for static launchers. We should specify the desired outcome, not what flags we should add. This can be seen as the last part of [JDK-8141444](https://bugs.openjdk.org/browse/JDK-8141444) (9 years later).

In the process, I am removing EXTRA_JAVA_ARGS which has not been used for a long time. I also removed this part from the launcher itself.

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Commit messages:
 - 8346669: Increase abstraction in SetupBuildLauncher and remove extra args

Changes: https://git.openjdk.org/jdk/pull/22832/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22832&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346669
  Stats: 105 lines in 12 files changed: 14 ins; 57 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/22832.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22832/head:pull/22832

PR: https://git.openjdk.org/jdk/pull/22832