[BUGFIX] Duplicated translation entry for clear cache menu pages

Remove duplicate translation entry in locallang_core.xlf

Change-Id: Ie550b4a8b9736e397a8ce46d00feb957652d92c0
Resolves: #55153
Releases: 6.2
Reviewed-on: https://review.typo3.org/26966
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters