Revert "Remove deprecated profiling config parameters, clarify docs"

StatCounter still needs $wgUDPProfilerHost.

This reverts commit 88c42dc1df93533286dfbe969631403f77958dca.

Change-Id: I4a56f6fb6bc454d15a9dc752f45dfb29b2b47a84
Merge "Revert "Remove deprecated profiling config parameters, clarify docs""