multi: add new config QuiescenceTimeout

This commit makes removes the `defaultQuiescenceTimeout` and makes it
configurable as different nodes have different network environment. In
addition the default timeout has been increased from 30s to 60s.

sample-lnd.conf

@@ -1913,6 +1913,10 @@
 ; are sent over a short period.
 ; htlcswitch.mailboxdeliverytimeout=1m
 
+; The max duration that the channel can be quiesced. Any dependent protocols
+; (dynamic commitments, splicing, etc.) must finish their operations under this
+; timeout value, otherwise the node will disconnect.
+; htlcswitch.quiescencetimeout=1m
 
 [grpc]