Allow overriding endpoints config as part of the prometheus service monitor scrape config

[mbalamaruthu]

Looking to add tls configs to the prometheus scrape config of the service endpoints but it looks like endpoints spec cannot be overridden ?

Wondering why the endpoint override was reverted? 9cdbce8#diff-59192eea607dc74ba7fe8083b44fcda4d965d41029c69ed16d2fc87bb505c0ae

Thanks