mediawiki.searchSuggest: Unbreak browser blacklist

The 'browsers' key is not supported nor used. The 'blacklist' used
here resulted in every browser being passed through.

Also remove the distinction between LTR and RTL languages, as the
blacklist for both is the same.

Change-Id: Ia72b8f29be94523b989c8d932e4525d8aad34422
Merge "mediawiki.searchSuggest: Unbreak browser blacklist"