itest: Add itest for bumpclosefeerate rpc.

Add an itest which will bump the close fee rate of an anchor
channel which is force closed without having any HTLCs at stake.

cmd/lncli/walletrpc_active.go

@@ -496,7 +496,7 @@ func bumpForceCloseFee(ctx *cli.Context) error {
 
 	// `sat_per_byte` was deprecated we only use sats/vbyte now.
 	if ctx.IsSet("sat_per_byte") {
-		return fmt.Errorf("deprecated, use sat_per_vbyte instead.")
+		return fmt.Errorf("deprecated, use sat_per_vbyte instead")
 	}
 
 	// Retrieve pending sweeps.