Unified default ack timeout to 30 seconds

Increased also default publish state timeout to 30 seconds (from 5 seconds) and introduced constant for it.
Introduced AcknowledgedRequest.DEFAULT_ACK_TIMEOUT constant (30 seconds).
Removed misleading timeout default values coming from the REST layer.
Removed (in a bw compatible manner) the timeout support in put/delete index template as the timeout parameter was ignored.

Closes #4395