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_timeout_resolver_test.go

@@ -390,7 +390,7 @@ func testHtlcTimeoutResolver(t *testing.T, testCase htlcTimeoutTestCase) {
 	go func() {
 		defer wg.Done()
 
-		_, err := resolver.Resolve(false)
+		_, err := resolver.Resolve()
 		if err != nil {
 			resolveErr <- err
 		}