Set `external_accounts` foreign key to users to be `ON DELETE CASCADE`

[maxachis]

Context

• Currently, if we delete from the users table, and the user in question has a row in EXTERNAL_ACCOUNTS, the deletion will be blocked because of that. The corresponding row in EXTERNAL_ACCOUNTS must be deleted first
• We can get around this by setting the foreign key in EXTERNAL_ACCOUNTS to ON DELETE CASCADE

Requirements

• Set the user_id foreign key in EXTERNAL_ACCOUNTS to ON DELETE CASCADE

Tests

• All tests should continue to run as expected

Docs

• No documentation should be affected

Open questions

• No open questions

[maxachis]

Currently made a minor adjustment to the dev_script to enable this, and pushed it directly to main. Not the most kosher, but figured I could get away with it since it's so minor, and can easily revoke it otherwise. Won't be able to do that in the future, but since it's still in dev, weeeee!

We'll see how it turns out tomorrow on the regular update.

[josh-chamberlain]

@maxachis I feel a duty to follow up—how did this turn out?

[maxachis]

@maxachis I feel a duty to follow up—how did this turn out?

Totally fine! Everything subsequently passed without issue!