Consistently only conditionally install tools in soundness checks

[simonjbeaumont]

Motivation

Some of the soundness checks rely on other tools, e.g. curl, yq, yamllint. These are installed as part of the command in the workflow. Some of them conditionally do this only if the tool wasn't detected as already installed; others check first, using which. The latter approach is better because it saves time performing the apt update and apt install commands if they are not necessary. In CI this is speed up in returning the check status and saves wasted compute. But it also has an important impact locally when running these checks is part of the developer workflow, usually with act.

Concretely, running soundness-format (an alias for the expanded act command to only run the format check) takes 38s in CI on a recent PR, but only 7s of this is actually running the check. The rest is pulling the Docker base image and doing the installation of curl.

Modifications

This PR updates all the soundness checks to be consistent with what we were already doing for the yamllint check: to only install missing tools.

As an aside, the use of apt was also inconsistent across the various soundness checks. This PR makes them consistent and:

• Replaces use of qq with q — the use of qq is strongly discouraged in the man page without a no-action specifier.
• Replaces use of apt-cache and apt-get with just apt, which has been supported for a long time.

Result

Faster CI, faster local workflow.

[FranzBusch]

LGTM!