Fix user gallery job pagination logic and add test for empty submission pages

- Updated pagination condition in `user_gallery_job.rb` to break when the number of pages is less than or equal to the current page.
- Added a new test case in `user_gallery_job_spec.rb` to handle scenarios with empty submission pages, ensuring no new records are created.
- Introduced a fixture file `api_search_empty_submissions.json` to simulate API responses with no submissions.

test/fixtures/files/domain/inkbunny/job/api_search_empty_submissions.json

@@ -0,0 +1,12 @@
+{
+  "sid": "9B5BPQqTZ,Mj-nYbL2tuIPoO,b",
+  "results_count_all": "0",
+  "results_count_thispage": 0,
+  "pages_count": 0,
+  "page": 0,
+  "user_location": "",
+  "rid": "520e18fe15",
+  "rid_ttl": "15 minutes",
+  "search_params": [],
+  "submissions": []
+}