Remove invalid connection checking in db_replicator

Account/Container-replicator checks connection generation and timeout
in HTTP REPLICATE Request in _repl_to_node, but it doesn't really checks
connection but only construction of ReplConnection class.
This patch removes that invalid checking.

Change-Id: Ie6b4062123d998e69c15638b741e7d1ba8a08b62
Closes-Bug: #1359018
Merge "Remove invalid connection checking in db_replicator"