Make HTTP connection parameters source-aware

Different replication sources may be located in different
geographical locations with their associated latencies and
timeouts.
Make the HTTP Client source-aware by allocating a separate
connection pool per source with associated timeouts.

HTTP Client gets automatically closed and reconfigured
upon source shutdown and automatic reload.

Feature: Issue 11605
Change-Id: I86419d1854ee405bae3abe947ed6a898c5c1d75b