[TASK] Remove label from clear cache button in docheader

In docheader buttons on the right side should not have labels,
therefore they are removed.

Resolves: #99215
Releases: main
Change-Id: Ief0a3f78132068905cdf10a35aa1cb8909fe3100
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76847


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Georg Ringer <georg.ringer@gmail.com>