Create a product variable for skipping apex contribution contents

This denylist will be used to ignore the prebuilt google apexes listed
in apex_contributions of vendor/google/build when building aosp products
in next.

Test: go build ./android
Bug: 308187268
Change-Id: Ib2c018a2aeda5578cf3f1a6a56253bf84850ba5f
Merged-In: Ib2c018a2aeda5578cf3f1a6a56253bf84850ba5f

android/config.go

@@ -2015,3 +2015,7 @@ func (c *config) AllApexContributions() []string {
 	}
 	return ret
 }
+
+func (c *config) BuildIgnoreApexContributionContents() []string {
+	return c.productVariables.BuildIgnoreApexContributionContents
+}