Remove use of actions/cache, which conflicts with caching done by actions/setup-go

[SarahFrench]

Fixes the errors we see in GHAs like this:

It looks like v4 of the actions/go-setup GHA enables caching by default, so when the action was updated to use a v4+ version of that action it started clashing with actions/cache.

This PR removes use of actions/cache and instead uses the caching features of go-setup. Internally this uses the same logic (actions/cache is used) but requires fewer inputs.

This matches what's already done in the equivalence test workflows, so a cache will be shared between more GHA workflows after this PR.

Target Release

N/A

CHANGELOG entry

• This change is user-facing and I added a changelog entry.
• This change is not user-facing.

[SarahFrench]

I initially started with the opposite approach of disabling caching in actions/setup-go and leaning actions/cache in the workflow, but figured it was best to go with simplicity.

[SarahFrench]

Looks like the test command step has a lot of go get...s happening - cache not being used?

Edit: I was wrong- the cache is used but for some reason there are some 'stragglers' that still need to be go get-ed when the step with the go test command runs. If you remove the cache entry and re-run the workflow the number of go gets increases massively.

tl;dr: This PR is ok for review again.

[dbanck]

Thanks for looking into this! These errors have been bothering me since I joined the team