[BUGFIX] Respect dots in TS keys during autocomplete

The code completion must differ between dots at the end and those in the
middle which belong to the key.

Instead of just replacing all dots, only the one at the end is used to
split the TS into chunks.

Resolves: #84534
Releases: master, 9.5
Change-Id: I82890b56d1a95584ddc079cc7e9c930cfaa71830
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63765


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>