web: use `SOURCEGRAPHDOTCOM_MODE` with `web-standalone`
Created by: valerybugakov
Context
Make it possible to change DOTCOM_MODE
via the local environment variable.
See related Slack thread.
A related issue for further improvements: https://github.com/sourcegraph/sourcegraph/issues/21870
Test plan
DOTCOM_MODE
should be false
for sg start web-standalone
.
DOTCOM_MODE
should be true
for SOURCEGRAPHDOTCOM_MODE=true sg start web-standalone
.