Make lots of tests run in parallel

Putting t.Parallel() in each test makes them run in parallel.
Additional t.Parallel() could be added to each subtest, although
that requires making a local copy of the loop variable for
table driven tests.

Test: m checkbuild
Change-Id: I5d9869ead441093f4d7c5757f2447385333a95a4
diff --git a/python/python_test.go b/python/python_test.go
index 23db24e..455d84a 100644
--- a/python/python_test.go
+++ b/python/python_test.go
@@ -326,6 +326,7 @@
 )
 
 func TestPythonModule(t *testing.T) {
+	t.Parallel()
 	for _, d := range data {
 		t.Run(d.desc, func(t *testing.T) {
 			config := android.TestConfig(buildDir, nil, "", d.mockFiles)