Remove the closed channel check for subscription channels.
 - Remove the closed channel check for subscription channels.

RB_ID=134854
 Fix concurrency issue while checking against an HChannel with the underlying channel as null
 The underlying channel is set to non null only *after* it is connected. This was causing a channel to remain open and hanging because it would be removed during the check in HChannelImpl. This change fixes it so that a null underlying channel is considered as open because we're only guarding against a channel that is not null but is closed.

RB_ID=135221
 Fix error in the read ahead cache
 The code was removing the installed stubs under the wrong condition.

RB_ID=135316
Enable logging in hedwig-server tests - this was unintentionally overwritten when integrating changes from the external repo

RB_ID=135256
we just clear shouldClaim flag for simple channel client but not for multiplex channel client. clear shouldClaim for multiplex channel client to make topics load balanced during resubscribed.

RB_ID=135706
 Use consumed until as a hint for per topic pending deliveries
 - Use consumed until as a hint for per topic pending deliveries

RB_ID=136111