Merge remote-tracking branch 'upstream/main' into feature/support-mer…

…gify

* upstream/main: (27 commits)
  Add Windows 2025 to CI (elastic#17133)
  Update container acceptance tests with stdout/stderr changes (elastic#17138)
  entrypoint: avoid polluting stdout (elastic#17125)
  Fix acceptance test assertions for updated plugin remove (elastic#17126)
  Fix acceptance test assertions for updated plugin `remove` (elastic#17122)
  plugins: improve `remove` command to support multiple plugins (elastic#17030)
  spec: improve ls2ls spec (elastic#17114)
  allow concurrent Batch deserialization (elastic#17050)
  CPM handle 404 response gracefully with user-friendly log (elastic#17052)
  qa: use clean expansion of LS tarball per fixture instance (elastic#17082)
  Allow capturing heap dumps in DRA BK jobs (elastic#17081)
  Use centralized source of truth for active branches (elastic#17063)
  Update logstash_releases.json (elastic#17055)
  fix logstash-keystore to accept spaces in values when added via stdin (elastic#17039)
  Don't honor VERSION_QUALIFIER if set but empty (elastic#17032)
  Release note placeholder might be empty, making parsing lines nil tolerant. (elastic#17026)
  Fix BufferedTokenizer to properly resume after a buffer full condition respecting the encoding of the input string (elastic#16968)
  Add short living 9.0 next and update main in CI release version definition. (elastic#17008)
  Core version bump to 9.1.0 (elastic#16991)
  Add 9.0 branch to the CI branches definition (elastic#16997)
  ...