Change docker command of cockroachDB module

[giger85]

This PR resolves #3571

Caveat

• Before v19.1.x version, start-single-node command does not work.

[rnorth]

EDIT: accidentally clicked the approve button 😬

[rnorth]

This is going to be problematic - it will mean that people who are using the default constructor in their tests will suddenly receive a different version of the container.

This is outlined further in #3381.

Also, we'll have a problem if start-single-node is not backwards compatible with older versions if CockroachDB. We can't break peoples' tests if they explicitly need to use older versions. Is it backwards compatible?

[giger85]

@rnorth
As #3571, current default tag version (v19.1.x) reached EOL and v20.2.x version is not working.

• https://www.cockroachlabs.com/docs/releases/release-support-policy

Since this module is incubating module, I thought this change is acceptable.
But start-single-node is not backward compatible command, I will try to find backward compatible solution.

Thanks for your review.

[bsideup]

@rnorth given the deprecated version and default tag being changed, I think we're good to go :) Will merge :)

Note that old versions can still be used by overriding the command, so we're not blocking the usage of them, just raising the minimal version requirement (again, since v19.1.x is EOL)

[giger85]

@bsideup
Thanks for your review.
This change helps for me :)