Check UseRBE is set before replacing any template with the RE version.

Test: presubmit
Change-Id: I6df58b4e700f0d231367af2710672d731d20a736
diff --git a/apex/builder.go b/apex/builder.go
index 0a1ec3e..27de00e 100644
--- a/apex/builder.go
+++ b/apex/builder.go
@@ -648,7 +648,7 @@
 		a.container_certificate_file,
 		a.container_private_key_file,
 	}
-	if ctx.Config().IsEnvTrue("RBE_SIGNAPK") {
+	if ctx.Config().UseRBE() && ctx.Config().IsEnvTrue("RBE_SIGNAPK") {
 		rule = java.SignapkRE
 		args["implicits"] = strings.Join(implicits.Strings(), ",")
 		args["outCommaList"] = a.outputFile.String()