chore: update ci/cd env vars, tests, examples for v2 api keys

[anitarua]

1. workflows move v1 api key to V1_API_KEY env var, sets MOMENTO_ENDPOINT to alpha endpoint, and sets MOMENTO_API_KEY to v2 api key
2. dependabot workflow wasn't adding "chore: " prefix, hindering auto-generated PRs for updating deps in examples
3. updated non-auth client examples to use v2 key
4. tests were to run using the new env vars (canaries will be updated to look for new env vars too). We decided to go with keeping the existing tests on v1 keys since auth client APIs are tied to v1 and most of our customers are still on v1. Added some happy path test cases to exercise v2 key but at some point later we should cut over most tests to v2 key.