Rebase and respond to Doug's comments

gcp/observability/config.go

@@ -57,9 +57,6 @@ func fetchDefaultProjectID(ctx context.Context) string {
 // validateMethodString validates whether the string passed in is a valid
 // pattern.
 func validateMethodString(method string) error {
-	if method == "*" {
-		return nil
-	}
 	if strings.HasPrefix(method, "/") {
 		return errors.New("cannot have a leading slash")
 	}

gcp/observability/logging.go

@@ -369,7 +369,7 @@ func (bl *binaryLogger) GetMethodLogger(methodName string) iblog.MethodLogger {
 // parseMethod splits service and method from the input. It expects format
 // "service/method".
 func parseMethod(method string) (string, string, error) {
-	pos := strings.LastIndex(method, "/")
+	pos := strings.Index(method, "/")
 	if pos < 0 {
 		// Shouldn't happen, config already validated.
 		return "", "", errors.New("invalid method name: no / found")