Update Prometheus `TextOutputFormat` so that OpenMetrics is used in preference to text output when an appropriate accept header is found. If the accept header contains `*/*` or is missing then the text format will be used. See gh-28130
Update Prometheus `TextOutputFormat` so that OpenMetrics is used in preference to text output when an appropriate accept header is found. If the accept header contains `*/*` or is missing then the text format will be used. See gh-28130