Allow specifying prometheus.server.endpoint without port

[sappusaketh]

Hello I have my prometheus running on example.com/prometheus specifying at present because of port num validation I have to specify the endpoint as https://example.com/prometheus:443 but doing so is making api calls to prometheus as https://example.com:443/api/v1/query_range which is returning 404 as :443 is included in path any chance we can add an option to ignore port and just use the url without port?