CI: Use the tox-verify workflow to test all envs

The previous tox CI config was not running "docs", which is not part
of the envlist. We will now run all necessary envs.

Due to how the tox-verify workflow functions, pre-commit no longer
needs to be separated out. All envs will be run in parallel.

Issue: RELENG-5138
Change-Id: I2c5e732b4fd0a28c800d7a3819fb8fb32a29e5fd
Signed-off-by: Eric Ball <eball@linuxfoundation.org>