Harden LDAP config discovery during login

[andrijapanicsb]

This stacks on top of apache#13152 and keeps the existing login-flow fix, while tightening a few edge cases found during review/testing.

Changes:

• Reset LDAP state with boolean false instead of {} during login/logout initialization.
• When listLdapConfigurations is unavailable during GetInfo, explicitly set SET_LDAP to false instead of leaving the previous truthy placeholder.
• Guard LDAP count parsing so an ignored 401 response does not throw from the then handler.
• Resolve UpdateLdapConfigurationFlag on success so callers waiting on the dispatch do not hang.
• Suppress the generic 401 notification for listLdapConfigurations, matching other optional discovery probes.

Validation:

• node --check ui/src/store/modules/user.js
• node --check ui/src/utils/request.js
• git diff --check