[jdk15u-dev] RFR: 8288650: Bump update version for OpenJDK: jdk-15.0.9

[Yuri Nesterenko]

This is a regular update switching team repository to the October, 2022 release.
Change is in the release number and the expected release date, and also in .jcheck/conf to instruct skara machinery do the switch.
The change will be pushed just after the last 15.0.8 build made from the team repo is tagged.

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Commit messages:
 - 8288650: Bump update version for OpenJDK: jdk-15.0.9

Changes: https://git.openjdk.org/jdk15u-dev/pull/224/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk15u-dev&pr=224&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8288650
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk15u-dev/pull/224.diff
  Fetch: git fetch https://git.openjdk.org/jdk15u-dev pull/224/head:pull/224

PR: https://git.openjdk.org/jdk15u-dev/pull/224