We should really make deleting from a slice a generic function imo. No need in this PR, just a comment

Originally posted by @Emyrk in #1770 (comment)

Instances:

• https://github.com/coder/coder/blob/main/coderd/database/databasefake/databasefake.go#L110
• https://github.com/coder/coder/blob/main/coderd/database/databasefake/databasefake.go#L1771

And another instance in #1770.