[CLEANUP] Always use HSC in TS labels in BE

The ExtendedTemplateService class contains
a switch "ext_noSpecialCharsOnLabels" which
is never used in the core. It is used to call a wrapper
function that simple doesn't do HSC() if the
option is set.

The method and option can be deprecated.

Releases: master
Resolves: #61513
Change-Id: I90e1f3728287b9f4dfa93f4cfc6875b5314a0eb3
Reviewed-on: http://review.typo3.org/32707
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>