Add created_at/updated_at timestamps to VPP apps teams table, return as added_at

[iansltx]

For #23744.

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information.
• Input data is properly validated, SELECT * is avoided, SQL injection is prevented (using placeholders for values in statements)
• If database migrations are included, checked table schema to confirm autoupdate
• For database migrations:
  • Checked schema for all modified table for columns that will auto-update timestamps during migration.
  • Confirmed that updating the timestamps is acceptable, and will not cause unwanted side effects.
  • Ensured the correct collation is explicitly set for character columns (COLLATE utf8mb4_unicode_ci).
• Added/updated automated tests
• A detailed QA plan exists on the associated ticket (if it isn't there, work with the product group's QA engineer to add it)
• Manual QA for all new/changed functionality

[iansltx]

Dropping manual backfill query out of this PR so it can get merged sooner. Will follow up with that a bit later. For reference, here's what pulled from the migration test:

	// test activity hydration manual query
	execNoErr(t, db, `INSERT INTO activities (activity_type, details, created_at) VALUES
		("added_app_store_app", '{"app_store_id":"a","team_id":null,"platform":"darwin"}', "2025-02-03 00:00:01"),
		("added_app_store_app", '{"app_store_id":"a","team_id":null,"platform":"darwin"}', "2025-02-03 00:00:02"),
		("edited_app_store_app", '{"app_store_id":"a","team_id":null,"platform":"darwin"}', "2025-02-03 00:00:03"),
		("edited_app_store_app", '{"app_store_id":"a","team_id":null,"platform":"darwin"}', "2025-02-03 00:00:04"),
		("added_app_store_app", '{"app_store_id":"a","team_id":1,"platform":"darwin"}', "2025-02-03 00:00:05"),
		("edited_app_store_app", '{"app_store_id":"a","team_id":1,"platform":"darwin"}', "2025-02-03 00:00:06"),
		("added_app_store_app", '{"app_store_id":"a","team_id":1,"platform":"ipados"}', "2025-02-03 00:00:07")
	`)

	execNoErr(t, db, `UPDATE vpp_apps_teams vat
LEFT JOIN (SELECT MAX(created_at) added_at, details->>"$.app_store_id" adam_id, details->>"$.platform" platform, details->>"$.team_id" team_id
    	FROM activities WHERE activity_type = 'added_app_store_app' GROUP BY adam_id, platform, team_id) aa ON 
	vat.team_id = aa.team_id AND vat.adam_id = aa.adam_id AND vat.platform = aa.platform
LEFT JOIN (SELECT MAX(created_at) edited_at, details->>"$.app_store_id" adam_id, details->>"$.platform" platform, details->>"$.team_id" team_id
		FROM activities WHERE activity_type = 'edited_app_store_app' GROUP BY adam_id, platform, team_id) ae ON
	vat.team_id = ae.team_id AND vat.adam_id = ae.adam_id AND vat.platform = ae.platform
SET vat.created_at = COALESCE(added_at, vat.created_at), vat.updated_at = COALESCE(edited_at, added_at, vat.updated_at)`)

	var rows []struct {
		Platform  string    `db:"platform"`
		TeamID    *uint64   `db:"team_id"`
		CreatedAt time.Time `db:"created_at"`
		UpdatedAt time.Time `db:"updated_at"`
	}

	require.NoError(t, db.Select(&rows, `SELECT platform, team_id, created_at, updated_at FROM vpp_apps_teams ORDER BY created_at, updated_at`))

	// no activities on iOS, so they keep the carry-over from the original query
	assert.Equal(t, "ios", rows[0].Platform)
	assert.Equal(t, appCreatedAt, rows[0].CreatedAt)
	assert.Equal(t, appUpdatedAt, rows[0].UpdatedAt)
	// no-team app with multiple events each
	assert.Nil(t, rows[1].TeamID)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 2, 0, time.UTC), rows[1].CreatedAt)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 4, 0, time.UTC), rows[1].UpdatedAt)
	// team 1 app with one event per type
	assert.Equal(t, uint(1), *rows[2].TeamID)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 5, 0, time.UTC), rows[2].CreatedAt)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 6, 0, time.UTC), rows[2].UpdatedAt)
	// team 1 app with only added event
	assert.Equal(t, "ipados", rows[3].Platform)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 7, 0, time.UTC), rows[3].CreatedAt)
	assert.Equal(t, time.Date(2025, 2, 3, 0, 0, 7, 0, time.UTC), rows[3].UpdatedAt)

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 8 lines in your changes missing coverage. Please review.

Project coverage is 63.86%. Comparing base (a748e92) to head (18ae045).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...tables/20250219100000_AddVPPAppsTeamsTimestamps.go	57.89%	6 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #26442      +/-   ##
==========================================
- Coverage   63.86%   63.86%   -0.01%     
==========================================
  Files        1661     1662       +1     
  Lines      159230   159252      +22     
  Branches     4109     4109              
==========================================
+ Hits       101700   101714      +14     
- Misses      49590    49596       +6     
- Partials     7940     7942       +2     

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backend	64.67% <66.66%> (-0.01%)	⬇️

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