Remove Android.bp file input to primaryBuilders

The soong primary builder action lists all the Android.bp files
as dependencies via a depfile. The top-level one doesn't need to be
listed as an input explicitly. I think it was there from the early
days of soong when soong started at the top-level Android.bp file and
traversed downwards through references via the subdirs or
optional_subdirs variables.

Bug: 364749114
Test: Presubmits
Change-Id: I72eabe4d4179696bfa258c8c4c56351a132e0870

ui/build/soong.go

@@ -244,7 +244,6 @@ func (pb PrimaryBuilderFactory) primaryBuilderInvocation(config Config) bootstra
 	globfiles := bootstrap.GlobFileListFiles(bootstrap.GlobDirectory(config.SoongOutDir(), globPathName))
 
 	return bootstrap.PrimaryBuilderInvocation{
-		Inputs:      []string{"Android.bp"},
 		Implicits:   globfiles,
 		Outputs:     []string{pb.output},
 		Args:        allArgs,