Status Checks - Add alert for bad foreign key

[totten]

Overview

Followup to #25380. If one disregards the upgrade notice, then the status-check should remind you.

Before

No status check.

After

The "Schema Error" appears if original_id has the ON DELETE CASCADE rule. What this means:

• It shows warning when you first extract new codebase -- before upgrading DB. (The screenshot shows this situation.)
• If you have small# activities, then the upgrader cleans the constraint. The warning goes away.
• If you have large# activities, then the upgrader leaves the constraint. The warning stays.
• If you drop the constraint (or didn't have it to begin with), then it shows no warning.

(I did r-run those scenarios on MySQL 5.7.)

Technical Details

According to https://stackoverflow.com/questions/12734331/constraint-detail-from-information-schema-on-update-cascade-on-delete-restrict, this metadata should be available in MySQL 5.1+.

[civibot]

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[totten]

test-1 barfed. Fired separate run for that job: https://test.civicrm.org/job/CiviCRM-Manual-Test/33/

[totten]

Re-run passed.