RCFilters: Only normalize title with 'target' when it is needed

We right now only need to normalize titles that are with subpages
into target= parameter in the RCLinked page. There's no need to do
that in RC or Watchlist, and it might interfere with other (or future)
features if we do.

This commit sets the normalization as conditional on a config
variable, that is given on initialization based on the proper
page we're in.

Change-Id: I288221edb143e0b3417e161062faf2eb4f9f9a51