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

ui/build/util_test.go

@@ -25,7 +25,6 @@ import (
 )
 
 func TestEnsureEmptyDirs(t *testing.T) {
-	t.Parallel()
 	ctx := testContext()
 	defer logger.Recover(func(err error) {
 		t.Error(err)
@@ -53,7 +52,6 @@ func TestEnsureEmptyDirs(t *testing.T) {
 }
 
 func TestCopyFile(t *testing.T) {
-	t.Parallel()
 	tmpDir, err := ioutil.TempDir("", "test_copy_file")
 	if err != nil {
 		t.Fatalf("failed to create temporary directory to hold test text files: %v", err)
@@ -88,7 +86,6 @@ func TestCopyFile(t *testing.T) {
 }
 
 func TestCopyFileErrors(t *testing.T) {
-	t.Parallel()
 	tmpDir, err := ioutil.TempDir("", "test_copy_file_errors")
 	if err != nil {
 		t.Fatalf("failed to create temporary directory to hold test text files: %v", err)