fix glean enrollments query with sample_id

[mikewilli]

Glean enrollments query uses UNNEST(events.events) as e instead of just events so we need to change the WHERE clause to remove the e. from sample_id.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (e4c9f30) 75.99% compared to head (33a9f2d) 75.99%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #192 +/- ## ======================================= Coverage 75.99% 75.99% ======================================= Files 23 23 Lines 958 958 ======================================= Hits 728 728 Misses 230 230 ``` | [Flag](https://app.codecov.io/gh/mozilla/mozanalysis/pull/192/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | Coverage Δ | | |---|---|---| | [py38](https://app.codecov.io/gh/mozilla/mozanalysis/pull/192/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | `75.99% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/mozilla/mozanalysis/pull/192?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | Coverage Δ | | |---|---|---| | [src/mozanalysis/experiment.py](https://app.codecov.io/gh/mozilla/mozanalysis/pull/192?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla#diff-c3JjL21vemFuYWx5c2lzL2V4cGVyaW1lbnQucHk=) | `78.50% <ø> (ø)` | |

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