Revert "Fixes #3622: Add a comparator for not matching a regex"

This reverts commit b58030adebb6fa9b7c690f7c83d0b02c8cd15bab.
This is a new feature that should not have been merged in
a bug-correction version.
Merge branch 'branches/rudder/2.6'
Fixes #3622: Add a comparator for not matching a regex