Remove yaml tests

Prior to this commit, some of our examples tests were duplicated as yaml tests.
The main difference between the two tests was that in examples tests, the yaml
was applied via `kubectl create`, and in the yaml tests, the yaml was applied
via `ko create`. However, the yaml tests no longer include PipelineRuns that
use images built by Tekton, so they are redundant with the examples tests.

This commit removes yaml tests, speeding up e2e test execution.

test/examples_test.go

@@ -20,11 +20,9 @@ limitations under the License.
 package test
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -99,14 +97,6 @@ func substituteEnv(input []byte, namespace string) ([]byte, error) {
 	return output, nil
 }
 
-// koCreate wraps the ko binary and invokes `ko create` for input within
-// namespace
-func koCreate(input []byte, namespace string) ([]byte, error) {
-	cmd := exec.Command("ko", "create", "--platform", "linux/"+getTestArch(), "-f", "-", "--", "--namespace", namespace)
-	cmd.Stdin = bytes.NewReader(input)
-	return cmd.CombinedOutput()
-}
-
 // deleteClusterTask removes a single clustertask by name using provided
 // clientset. Test state is used for logging. deleteClusterTask does not wait
 // for the clustertask to be deleted, so it is still possible to have name
@@ -235,15 +225,6 @@ func TestExamples(t *testing.T) {
 	testYamls(t, "../examples", kubectlCreate, pf)
 }
 
-func TestYamls(t *testing.T) {
-	pf, err := getPathFilter(t)
-	if err != nil {
-		t.Fatal(err.Error())
-		return
-	}
-	testYamls(t, "./yamls", koCreate, pf)
-}
-
 func testYamls(t *testing.T, baseDir string, createFunc createFunc, filter pathFilter) {
 	t.Parallel()
 	for _, path := range getExamplePaths(t, baseDir, filter) {