RFR: 8366232: JFR startup messages are shown with -Xlog:jfr+startup=warning [v2]

[Johannes Bechberger]

> Only print the JFR startup messages when no or a < warning log level is set explicitly by the user.

Johannes Bechberger 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 'openjdk:master' into parttimenerd_fix_startup
 - Fix startup message printing

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26957/files
  - new: https://git.openjdk.org/jdk/pull/26957/files/95c47b2a..56cef57f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26957&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26957&range=00-01

  Stats: 46693 lines in 1755 files changed: 26974 ins; 11155 del; 8564 mod
  Patch: https://git.openjdk.org/jdk/pull/26957.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26957/head:pull/26957

PR: https://git.openjdk.org/jdk/pull/26957