chore(csql): update iam user as impersonated user

Author: kgala2

.github/workflows/tests.yml

@@ -74,7 +74,7 @@ jobs:
             MYSQL_DB:${{ vars.GOOGLE_CLOUD_PROJECT }}/MYSQL_DB
             POSTGRES_CONNECTION_NAME:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_CONNECTION_NAME
             POSTGRES_USER:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_USER
-            POSTGRES_IAM_USER:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_USER_IAM
+            POSTGRES_IAM_USER:${{ vars.GOOGLE_CLOUD_PROJECT }}/IMPERSONATED_USER
             POSTGRES_PASS:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_PASS
             POSTGRES_DB:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_DB
             POSTGRES_CAS_CONNECTION_NAME:${{ vars.GOOGLE_CLOUD_PROJECT }}/POSTGRES_CAS_CONNECTION_NAME