Drop 2 unneeded sequences showing up in database diagnostics page

What does this MR do and why?

The database diagnostics page is flagging two sequences that are missing some from installations:

1. project_incident_management_settings_project_id_seq
2. user_statuses_user_id_seq

We can safely drop them because the corresponding columns are foreign key columns that reference primary keys in other tables, so auto-incrementing the value doesn't make sense:

1. project_incident_management_settings.project_id references projects.id.
2. user_statuses.user_id references users.id.

References

Relates to https://gitlab.com/gitlab-com/request-for-help/-/issues/3342

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