Remove extraneous calls to TestingBuildParams.RelativeToTop()

Deprecated the method to try and prevent any other uses being added.

Bug: 183650682
Test: m nothing
Change-Id: Ia6f43851e5a00c9d96af780e3bd21e03175e1a2f
diff --git a/android/testing.go b/android/testing.go
index f4f5c98..ce27fca 100644
--- a/android/testing.go
+++ b/android/testing.go
@@ -551,6 +551,8 @@
 //   * CommandOrderOnly
 //
 // See PathRelativeToTop for more details.
+//
+// deprecated: this is no longer needed as TestingBuildParams are created in this form.
 func (p TestingBuildParams) RelativeToTop() TestingBuildParams {
 	// If this is not a valid params then just return it back. That will make it easy to use with the
 	// Maybe...() methods.