Remove CockroachDB storage provider from Rook due to lack of community support

[travisn]

Is this a bug report or feature request?

• Bug Report

Deviation from expected behavior:
The CockroachDB storage provider has not had sufficient community or maintainer support to continue to release its operator as part of Rook. The proposal is to remove CockroachDB from Rook in the v1.6 release (March timeline).

See the full proposal here.

Expected behavior:
Storage providers in Rook must have community and maintainer support. This has been discussed for the past two Rook community meetings as seen in the notes. Also see the related expectations for storage providers now being documented in #6989.