feat: no longer accept the endpoint on the command line

[peterguy]

The endpoint on the command line always had to match SRC_ENDPOINT, which defaults to https://sourcegraph.com; there was no point to supporting the command-line argument.

This could be considered a "breaking change" because the error The configured endpoint is [SRC_ENDPOINT], not [command-line-arg]. Will no longer show up.

It has been replaced by a usage error: src login no longer accepts a URL argument; set SRC_ENDPOINT instead

Before:

After:

Test plan

CI tests updated.

[burmudar]

I think we should keep --endpoint. gh supports a similar arg with gh auth login --hostname enterprise.internal

SRC_ENDPOINT should only be used when you don't specify --endpoint. If SRC_ENDPOINT and --endpoint are specified - we should print a warning and say that we are going to use --endpoint over SRC_ENDPOINT.

I think for agents it also might be easier to use --endpoint, for instance to first set SRC_ENDPOINT and then src login requires two tool calls while src login --endpoint http://sourcegraph.example.com requires one.

Also just to diagnose things quickly on your own you might have SRC_ENDPOINT defined to sg.prod but then you quickly want to verify against staging sg.staging now you have to export SRC_ENDPOINT=sg.internal; src login; export SRC_ENDPOINT=sg.prod; whereas you could just from the start do src login --endpoint sg.internal.

[keegancsmith]

Agreed, we should keep it but change the enforcement. I don't know why that existed before? Maybe it should only warn if SRC_ENDPOINT is set