Rename school search type to gias_school

Previously this location type was known as `school` but has been renamed
to `gias_school` to make it clearer what this type represents.

Jira-Issue: MAV-5556

Author: thomasleese

mavis/test/data_models.py

@@ -71,7 +71,7 @@ def get_from_testing_api(
         def _get_schools_with_year_group(year_group: int) -> list[School]:
             url = urllib.parse.urljoin(base_url, "api/testing/locations")
             params = {
-                "type": "school",
+                "type": "gias_school",
                 "status": "open",
                 "is_attached_to_team": "false",
                 "gias_year_groups[]": [str(year_group)],