Story: As a registry user, I still want to be able to use Quay when LDAP is temporarily down for functionality that does not require LDAP (e.g. robot or API tokens) so that my CI pipelines continue to work.

Background: Today, LDAP uptime is a hard requirement for the registry to operator. If there is any issue with LDAP, Quay will crash and keep crash-looping on startup because the LDAP validation is part of the startup check sequence of the Quay pod.

Acceptance criteria:

• transient LDAP failures do not cause Quay to shutdown / crash
• if there is no connectivity to LDAP, operations that don't require LDAP should continue to work
• it is acceptable if the UI or any operation that requires LDAP to be online for verifying users does not work
• Human-readable error messages in the Quay pod log should indicate that LDAP is down or having transient issues