Trivial removing an unused gc-cause; it was previously used by Parallel only.
------------- Commit messages: - remove-gc-cause Changes: https://git.openjdk.org/jdk/pull/20403/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20403&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8337546 Stats: 13 lines in 4 files changed: 0 ins; 11 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/20403.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20403/head:pull/20403 PR: https://git.openjdk.org/jdk/pull/20403
