Update firebase_admin/_auth_utils.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: KetanHegde

firebase_admin/_auth_utils.py

@@ -81,6 +81,8 @@ def get_emulator_host():
 
 def get_tenant_emulator_host():
     emulator_host = os.getenv(TENANT_EMULATOR_HOST_ENV_VAR, '')
+    if not emulator_host:
+        emulator_host = get_emulator_host()
     if emulator_host and '//' in emulator_host:
         raise ValueError(
             f'Invalid {TENANT_EMULATOR_HOST_ENV_VAR}: "{emulator_host}". '