remove volta from CI

[mansona]

This PR attempts to just use the standard actions/setup-node infra to setup node because the volta infra keeps crashing on us

[void-mAlex]

seems like the one test that is failing is related directly to volta shenanigans ... we may need to see how that translates in a world without volta
https://github.com/void-mAlex/embroider/blob/main/tests/scenarios/shared-internals-test.ts#L44

[ef4]

If we're going to remove Volta lets do it everywhere, in favor of using pnpm's built-in node version management via npmrc files.

The tests that need a specific node version should emit their own npmrc files, similar to how they emit their own Volta config now.

[ef4]

Volta maintainers discussing a fix: volta-cli/volta#1523 (comment)

[mansona]

I'm submitting this PR for consideration again. I have implemented the pnpm node version management for the tests that need it but I have not implemented it across the board.

My reasoning for this is that we specifically have tests that use --no-lockfile because we want to track when our CI is failing because of changes in our dependencies. With volta and pnpm's use-node-version implementation you have to pin an exact version of node which does not seem in the spirit of --no-lockfile. This PR also identified the problem that I describe in #1649 because it also didn't pin an exact version of pnpm

I will add this PR to the meeting agenda for discussion 👍