Revert "1) Added support for Kerberos authentication, using SPNEGO to forward the Kerberos tickets through a browser. Fixes #5457"

This reverts commit 6ead597b43.

web/pgadmin/__init__.py

@@ -43,7 +43,6 @@ from pgadmin.utils.ajax import internal_server_error, make_json_response
 from pgadmin.utils.csrf import pgCSRFProtect
 from pgadmin import authenticate
 from pgadmin.utils.security_headers import SecurityHeaders
-from pgadmin.utils.constants import KERBEROS
 
 # Explicitly set the mime-types so that a corrupted windows registry will not
 # affect pgAdmin 4 to be load properly. This will avoid the issues that may
@@ -696,19 +695,11 @@ def create_app(app_name=None):
                 )
                 abort(401)
             login_user(user)
-        elif config.SERVER_MODE and\
-                app.PGADMIN_EXTERNAL_AUTH_SOURCE ==\
-                KERBEROS and \
-                not current_user.is_authenticated and \
-                request.endpoint in ('redirects.index', 'security.login'):
-            return authenticate.login()
 
         # if the server is restarted the in memory key will be lost
         # but the user session may still be active. Logout the user
         # to get the key again when login
         if config.SERVER_MODE and current_user.is_authenticated and \
-                app.PGADMIN_EXTERNAL_AUTH_SOURCE != \
-                KERBEROS and \
                 current_app.keyManager.get() is None and \
                 request.endpoint not in ('security.login', 'security.logout'):
             logout_user()