fix(capman): emit the bytes scanned metric from db_query

[volokluev]

closes https://getsentry.atlassian.net/browse/SNS-2812

Right now the bytes_scanned metric that is used in our customer dashboard and our API abuse dashboard is emitted from the BytesScannedWindowAllocationPolicy (code)

There is a plan to deprecate the BytesScannedWindowPolicy and it already does not exist on replays and spans.

This breaks that dashboard.

This metric should be emitted independently of any policy at a higher level (e.g. db_query)

[codecov]

Test Failures Detected: Due to failing tests, we cannot provide coverage reports at this time.

❌ Failed Test Results:

Completed 2470 tests with 1 failed, 2465 passed and 4 skipped.

View the full list of failed tests

pytest

• Test name: tests.web.test_db_query::test_db_record_bytes_scanned
  
  

  Traceback (most recent call last):
    File ".../tests/web/test_db_query.py", line 278, in test_db_record_bytes_scanned
      assert metrics[0].tags == {
  AssertionError: assert {'dataset': 'events', 'referrer': 'something', 'storage_key': 'errors_ro'} == {'dataset_name': 'events', 'referrer': 'something', 'storage_key': 'errors_ro'}
    Common items:
    {'referrer': 'something', 'storage_key': 'errors_ro'}
    Left contains 1 more item:
    {'dataset': 'events'}
    Right contains 1 more item:
    {'dataset_name': 'events'}
    Full diff:
    - {'dataset_name': 'events', 'referrer': 'something', 'storage_key': 'errors_ro'}
    &          -----
    + {'dataset': 'events', 'referrer': 'something', 'storage_key': 'errors_ro'}

[nachivrn]

Looks good.