Revert "Make lots of tests run in parallel"

This reverts commit 323dc60712.

Reason for revert: Possible cause of test instability
Bug: 170513220
Test: soong tests

Change-Id: Iee168e9fbb4210569e6cffcc23e60d111403abb8

genrule/genrule_test.go

@@ -125,7 +125,6 @@ func testConfig(bp string, fs map[string][]byte) android.Config {
 }
 
 func TestGenruleCmd(t *testing.T) {
-	t.Parallel()
 	testcases := []struct {
 		name string
 		prop string
@@ -504,7 +503,6 @@ func TestGenruleCmd(t *testing.T) {
 }
 
 func TestGenruleHashInputs(t *testing.T) {
-	t.Parallel()
 
 	// The basic idea here is to verify that the sbox command (which is
 	// in the Command field of the generate rule) contains a hash of the
@@ -592,7 +590,6 @@ func TestGenruleHashInputs(t *testing.T) {
 }
 
 func TestGenSrcs(t *testing.T) {
-	t.Parallel()
 	testcases := []struct {
 		name string
 		prop string
@@ -685,7 +682,6 @@ func TestGenSrcs(t *testing.T) {
 }
 
 func TestGenruleDefaults(t *testing.T) {
-	t.Parallel()
 	bp := `
 				genrule_defaults {
 					name: "gen_defaults1",