feat(ddm): Add 'project' as a key to the tags for metrics

[shellmayr]

Closes https://github.com/getsentry/sentry/issues/68417

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.70%. Comparing base (1a732c3) to head (0848cc1). Report is 3 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #69286 +/- ## ========================================== - Coverage 79.70% 79.70% -0.01% ========================================== Files 6431 6431 Lines 286001 286004 +3 Branches 49300 49300 ========================================== + Hits 227963 227965 +2 - Misses 57601 57602 +1 Partials 437 437 ``` | [Files](https://app.codecov.io/gh/getsentry/sentry/pull/69286?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getsentry) | Coverage Δ | | |---|---|---| | [src/sentry/snuba/metrics/datasource.py](https://app.codecov.io/gh/getsentry/sentry/pull/69286?src=pr&el=tree&filepath=src%2Fsentry%2Fsnuba%2Fmetrics%2Fdatasource.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getsentry#diff-c3JjL3NlbnRyeS9zbnViYS9tZXRyaWNzL2RhdGFzb3VyY2UucHk=) | `97.34% <100.00%> (+0.01%)` | :arrow_up: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/getsentry/sentry/pull/69286/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=getsentry)

[sentry-io[bot]]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ AssertionError: assert [] == [{'key': 'project'}] pytest.runtest.protocol tests/sentry/api/endpoi... View Issue
• ‼️ AssertionError: assert [] == [{'key': 'env...': 'project'}] pytest.runtest.protocol tests/sentry/api/endpoi... View Issue

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