remove part with workload identity federation

Author: luxzoli

notebook/gemini_vertexai.ipynb

@@ -133,12 +133,7 @@
     "\n",
     "If you are using [Cloud Shell](https://shell.cloud.google.com/cloudshell) or [Cloud Shell editor](https://shell.cloud.google.com/cloudshell/editor) in Google cloud, <br/> then you are already authenticated. If you have the Google Cloud SDK installed locally,  <br/> then you can login by running `gcloud auth login` in the command line. \n",
     "\n",
-    "Detailed instructions for installing the Google CLoud SDK can be found [here](https://cloud.google.com/sdk/docs/install).\n",
-    "\n",
-    "#### Workload Identity Federation\n",
-    "One could also use Workload Identity Federation, which is more secure than simply using service account key files. More information on the topic is found [here](https://cloud.google.com/iam/docs/workload-identity-federation). Another tutorial on this topic can be found on the [official GCP blog](https://cloud.google.com/blog/products/identity-security/enable-keyless-access-to-gcp-with-workload-identity-federation/). \n",
-    "\n",
-    "This method also relies on setting `GOOGLE_APPLICATION_CREDENTIALS`, so one can simply reuse the pattern already described for using service account key files, where the only difference is the content of the credentials file. "
+    "Detailed instructions for installing the Google CLoud SDK can be found [here](https://cloud.google.com/sdk/docs/install)."
    ]
   },
   {