fix: fix/skip some broken tests (#3991)

* allow profiler tests to run without a protobuf error

* exclude profiler outputs from the badfiles test.

* Mark this as an example test, instead of a real test.

This example was removed some time ago, and testing another sample would
be redundant.

* skip securitycenter unmute tests, which are failing as reported in #3793

* remove outdated testing docs. CONTRIBUTING.md has current guidance.

---------

Co-authored-by: Remigiusz Samborski <rsamborski@users.noreply.github.com>
Co-authored-by: gcf-merge-on-green[bot] <60162190+gcf-merge-on-green[bot]@users.noreply.github.com>
Co-authored-by: Brenna N Epp <brennae@google.com>

Makefile

@@ -12,6 +12,9 @@ INTERFACE_ACTIONS="build test lint"
 export GOLANG_SAMPLES_E2E_TEST ?= true
 export GOLANG_SAMPLES_PROJECT_ID ?=${GOOGLE_SAMPLES_PROJECT}
 
+# Required for cloud profiler tests to run
+export GOLANG_PROTOBUF_REGISTRATION_CONFLICT=warn
+
 build:
 	go -C ${dir} build .
 

badfiles_test.go

@@ -91,6 +91,9 @@ var allowList = []string{
 	// Cloud Functions gen2 picture.
 	"functions/functionsv2/imagemagick/zombie.jpg",
 
+	// Cloud Profiler test outputs
+	"profiler/export/**",
+
 	// Samples that aren't really code. Legacy.
 	"**/appengine/**/*.txt",
 

securitycenter/muteconfig/mute_config_test.go

@@ -251,6 +251,7 @@ func TestSetMuteFinding(t *testing.T) {
 }
 
 func TestSetUnmuteFinding(t *testing.T) {
+	t.Skip("see https://github.com/GoogleCloudPlatform/golang-samples/issues/3793")
 	testutil.SystemTest(t)
 
 	var buf bytes.Buffer