What tests and CI jobs do we want to _stop_ running for every PR in CI?

[arya2]

We want to:

• reduce redundant or unnecessary validation steps in CI that currently run for every PR, and
• decide what tests and CI jobs to run on before releases, on main, on every PR, and in git commit/push hooks.

[conradoplg]

• Anything with Rust beta - the goal is to become aware of breaking changes in beta Rust before it is released; it does not make sense to block a PR on that. IMO it should run weekly
• MSRV clippy - we just need it to build on MSRV; running clippy leads to false positives for rules that have changed in recent Rust
• deny advisories - fails for reasons independent from specific PRs; should run weekly

[mpguerra]

Let's start with these 3

[arya2]

Proposal: Let's stop running any CI per PR/commit, reduce the CI checks on the merge queue staging PR to just 'fmt / lint'

We could instead create tags every few hours named after the level of validation that was applied to the tag, run basic validation for every tag, more extensive validation once per day/week.

If there's ever an issue we can start doing a git bisect starting at the last tag that passed validation.

[conradoplg]

Not a fan, I think it would add more work to find where errors were introduced, and introducing the risk of releasing broken stuff. And I think the current CI checks are reasonably fast for regular reasons. If the goal is to allow merging faster I'm in favor of allow bypassing CI manually if there is justification