[BUGFIX] Remove wrong RewriteBase in _.htaccess

The configuration now works independently of RewriteBase,
hence we must not define one.

Resolves: #67922
Releases: master, 6.2
Change-Id: Ib1e14f808fbf2e7abd08a4e85d2a3d4e8509060a
Reviewed-on: http://review.typo3.org/40929


Reviewed-by: Frederic Gaus <frederic.gaus@flagbit.de>
Tested-by: Frederic Gaus <frederic.gaus@flagbit.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>