Remove unused remember_created_at user column

[aduth]

🛠 Summary of changes

Removes the remember_created_at column from the users table.

This field is not currently used, and as best I can tell has never been referenced as far back as #1.

📜 Testing Plan

Verify migration runs cleanly:

rails db:migrate

Verify no lingering references to the removed column.

[zachmargolis]

LGTM but because we have our code set to use explicit columns in SELECT statements, I think we need to add it as an ignored column first and then drop it in a second PR

[aduth]

LGTM but because we have our code set to use explicit columns in SELECT statements, I think we need to add it as an ignored column first and then drop it in a second PR

Ah, good call. I'll spin up a separate pull request for that.

[aduth]

LGTM but because we have our code set to use explicit columns in SELECT statements, I think we need to add it as an ignored column first and then drop it in a second PR

Do we document this anywhere?

[zachmargolis]

LGTM but because we have our code set to use explicit columns in SELECT statements, I think we need to add it as an ignored column first and then drop it in a second PR

Do we document this anywhere?

If you read between the lines a bit, yes. (We could probably embellish that section of the page a bit)

[zachmargolis]

LGTM but because we have our code set to use explicit columns in SELECT statements, I think we need to add it as an ignored column first and then drop it in a second PR

Do we document this anywhere?

If you read between the lines a bit, yes. (We could probably embellish that section of the page a bit)

PR to add documentation here: GSA-TTS/identity-handbook#538