contractcourt: remove the immediate param used in Resolve

This `immediate` flag was added as a hack so during a restart, the
pending resolvers would offer the inputs to the sweeper and ask it to
sweep them immediately. This is no longer need due to `blockbeat`, as
now during restart, a block is always sent to all subsystems via the
flow `ChainArb` -> `ChannelArb` -> resolvers -> sweeper. Thus, when
there are pending inputs offered, they will be processed by the sweeper
immediately.

contractcourt/htlc_outgoing_contest_resolver_test.go

@@ -209,7 +209,7 @@ func (i *outgoingResolverTestContext) resolve() {
 	// Start resolver.
 	i.resolverResultChan = make(chan resolveResult, 1)
 	go func() {
-		nextResolver, err := i.resolver.Resolve(false)
+		nextResolver, err := i.resolver.Resolve()
 		i.resolverResultChan <- resolveResult{
 			nextResolver: nextResolver,
 			err:          err,