Remove explicit HLToks since full HLT folder is already vetoed

Hi @jchapman,

as far as I understand, the 21.3 cmake warning:

Ignored these rule(s) while selecting packages to build:

     - HLT/HLToks

  Make sure that you didn't make a typo, and that there is no duplicate in:

     /build2/atnight/localbuilds/nightlies/21.3/athena/Projects/Athena/package_filters.txt

is showing up since HLT/HLToks is explicitly removed from compilation, although before, the full HLT directory is already removed.

So this MR should fix the warning.

Best, Nico