[Desktop] Expired ad conversion is not removed from database

[btlechowski]

Follow up to #10240

Steps to Reproduce

1. Run Brave that points to ads staging server
2. Download catalog 10240 expire.txt
3. In the catalog change endAt to now()+4hours. the conversion's expire date will be endAt+24h
4. Load the ad catalog
5. Open brave.com and trigger the ad
6. Close the browser
7. Make the conversion expire
8. Run Brave
9. Open https://www.interia.pl/ to trigger conversion
10. Check if the entry in the database(Default/ads_service/bundfle_state sqlite ad_conversions) was deleted

Important: The conversion is not triggered, which is good

Actual result:

The entry in the database(Default/ads_service/bundfle_state sqlite ad_conversions) was not deleted:

Expected result:

The entry is deleted

Reproduces how often:

100% repro rate

Brave version (brave://version info)

Brave	1.11.90 Chromium: 83.0.4103.116 (Official Build) dev (64-bit)
Revision	8f0c18b4dca9b6699eb629be0f51810c24fb6428-refs/branch-heads/4103@{#716}
OS	Ubuntu 18.04 LTS

cc @brave/legacy_qa @rebron @tmancey

[LaurenWags]

Reproduced on macOS

Brave	1.11.90 Chromium: 83.0.4103.116 (Official Build) dev (64-bit)
Revision	8f0c18b4dca9b6699eb629be0f51810c24fb6428-refs/branch-heads/4103@{#716}
OS	macOS Version 10.14.6 (Build 18G3020)

[tmancey]

@LaurenWags @btlechowski Discussed with @btlechowski as we only remove expired ad conversions once the catalog updates with a new catalog (i.e. the catalog id changes). This is not an issue as expired ad conversions are ignored when checking for new conversions. Thanks