Add build flag to enable ResourceProcessorBusyBox by default

Setting the RELEASE_USE_RESOURCE_PROCESSOR_BY_DEFAULT build flag will
change the default for use_resource_processor from false to true.

Bug: 294256649
Test: builds
Change-Id: If643bf8db9e2e039200f63f4aac226ed5b44d9e0

android/config.go

@@ -1970,6 +1970,10 @@ func (c *config) GetBuildFlag(name string) (string, bool) {
 	return val, ok
 }
 
+func (c *config) UseResourceProcessorByDefault() bool {
+	return c.productVariables.GetBuildFlagBool("RELEASE_USE_RESOURCE_PROCESSOR_BY_DEFAULT")
+}
+
 var (
 	mainlineApexContributionBuildFlags = []string{
 		"RELEASE_APEX_CONTRIBUTIONS_ADSERVICES",