RFR: JDK-8297215: Update libs tests to use @enablePreview [v3]

[Joe Darcy]

> Similar to an update recently done for langtools tests, update the libraries regression tests to take advantage of the @enablePreview jtreg feature.

Joe Darcy 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 four additional commits since the last revision:

 - Respond to review feedback.
 - Merge branch 'master' into JDK-8297215
 - Respond to review feedback.
 - JDK-8297215: Update libs tests to use @enablePreview

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11222/files
  - new: https://git.openjdk.org/jdk/pull/11222/files/f3fc9e26..6d11bbca

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11222&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11222&range=01-02

  Stats: 47274 lines in 976 files changed: 24551 ins; 8961 del; 13762 mod
  Patch: https://git.openjdk.org/jdk/pull/11222.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11222/head:pull/11222

PR: https://git.openjdk.org/jdk/pull/11222