RFR: 8267465: remove superfluous preview related annotations and test options [v2]

[Vicente Romero]

> Please review this PR which is removing several superfluous `@SuppressWarnings("preview")` annotations from the compiler code and also removing preview related, but not needed anymore, options from regression tests. Please also review the related CSR which covers the only case that modified a public API.
> 
> TIA

Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into JDK-8267465
 - 8267465: remove superfluous @SuppressWarnings(preview) annotations

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4330/files
  - new: https://git.openjdk.java.net/jdk/pull/4330/files/81162e72..fab606ce

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4330&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4330&range=00-01

  Stats: 34827 lines in 1340 files changed: 25154 ins; 5460 del; 4213 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4330.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4330/head:pull/4330

PR: https://git.openjdk.java.net/jdk/pull/4330