Remove pat and ssh enforcement database columns

What does this MR do and why?

Describe in detail what your merge request does and why.

• Removes enforce_pat_expiration and enforce_ssh_key_expiration columns from application_settings table.
• Both columns have been ignored for several milestones.

Database Review

Migrate

main: == 20220720121421 RemovePatAndSshEnforcementColumnsFromApplicationSettings: migrating
main: -- remove_column(:application_settings, :enforce_pat_expiration, :boolean, {:default=>false, :null=>false})
main:    -> 0.0047s
main: -- remove_column(:application_settings, :enforce_ssh_key_expiration, :boolean, {:default=>false, :null=>false})
main:    -> 0.0022s
main: == 20220720121421 RemovePatAndSshEnforcementColumnsFromApplicationSettings: migrated (0.0079s)

Rollback

main: == 20220719095015 RemovePatAndSshEnforcementColumnsFromApplicationSettings: reverting
main: -- add_column(:application_settings, :enforce_pat_expiration, :boolean, {:null=>false, :default=>true})
main:    -> 0.0055s
main: -- add_column(:application_settings, :enforce_ssh_key_expiration, :boolean, {:null=>false, :default=>true})
main:    -> 0.0015s
main: == 20220719095015 RemovePatAndSshEnforcementColumnsFromApplicationSettings: reverted (0.0092s)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #359942 (closed)