Re-fix missing data in "focus identification" auth

Improves the message emitted when no username (or other required piece
of information) is entered in "focus identification" module:
Instead of "please try later" we now provide "Invalid username and/or
password". It is still not 100% OK, but certainly better.

Related to MID-8726.

model/authentication-impl/src/main/java/com/evolveum/midpoint/authentication/impl/provider/FocusIdentificationProvider.java

@@ -25,6 +25,7 @@
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.authentication.AuthenticationServiceException;
+import org.springframework.security.authentication.BadCredentialsException;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.AuthenticationException;
@@ -65,9 +66,10 @@ protected Authentication internalAuthentication(Authentication authentication, L
             if (authentication instanceof FocusVerificationToken) {
                 Map<ItemPath, String> attrValuesMap = (Map<ItemPath, String>) authentication.getDetails();
                 if (attrValuesMap == null || attrValuesMap.isEmpty()) {
-                    // E.g. no user name provided when resetting the password (hence DEBUG, not ERROR)
+                    // E.g. no user name or other required property provided when resetting the password.
+                    // Hence DEBUG, not ERROR, and BadCredentialsException, not AuthenticationServiceException.
                     LOGGER.debug("No details provided: {}", authentication);
-                    throw new AuthenticationServiceException("web.security.provider.unavailable"); // TODO better message key!
+                    throw new BadCredentialsException(AuthUtil.generateBadCredentialsMessageKey(authentication));
                 }
                 ModuleAuthentication moduleAuthentication = AuthUtil.getProcessingModule();
                 List<ModuleItemConfigurationType> itemsConfig = null;