drop CC 'local-prefix' feature

It is not entirely clear to me what this used to do once, but I've stumbled
upon this before. By now I am certain that this is a non-standard legacy
feature. The BSC does *not* redirect connections during CC transactions.

Along with this, a bunch of legacy utility functions can be dropped. All of
this is unused code.

(Preparing for MSC pooling.)

Change-Id: Id54afe8ccf0e11b9121a733224054c9565eafb58
5 files changed