feat: allow starting docker container via env variable

[btkostner]

Fixes #87043 by allowing you to specify args via the COCKROACH_ARGS env value instead of a command. This is required to be able to use the official cockroach image with GitHub actions via a service. More details in the issue.

Note, do to weirdness with merging commands and env values, I decided that setting the COCKROACH_ARGS would ignore any command given. This should reduce issues with people trying to use both ways of specifying args and instead force them to pick one.

Release note (general change): Allow setting docker command args via the COCKROACH_ARGS environment variable.

[cockroach-teamcity]

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[cockroach-teamcity]

This change is 

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[rickystewart]

Thanks for the contribution!

bors r+

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)