[TASK] Adjust rst syntax for proper yaml highlighting

Define default highlighting for 86365 changelog entry to be yaml. Adjust
all yaml occurrences within this entry to use default highlighting.

Releases: master
Resolves: #86365
Change-Id: I9063311830330d55ae051c8a0d38da78a2a91831
Reviewed-on: https://review.typo3.org/58514


Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>