toYaml - Fixes #3470 - trailing \n issue

`toYaml` was introducing a new line. It is an issue since the new line is part of a functions output, it can't be whitespace chomped away so it would require a `trimSuffix "\n"` pipe. This commit trims one trailing `\n` from the toYaml output.

(cherry picked from commit 6cdf6cee)

pkg/strvals/parser.go

@@ -36,7 +36,7 @@ func ToYAML(s string) (string, error) {
 		return "", err
 	}
 	d, err := yaml.Marshal(m)
-	return string(d), err
+	return strings.TrimSuffix(string(d), "\n"), err
 }
 
 // Parse parses a set line.