chore(ci): remove unused recordings (#4074)

Added a script to cleanup recordings. While doing this, moved the CI
matrix generation to a separate script so there is a single source of
truth for the matrix.

Ran the cleanup script as:
```
PYTHONPATH=. python scripts/cleanup_recordings.py
```

Also added this as part of the pre-commit workflow to ensure that the
recordings are always up to date and that no stale recordings are left
in the repo.

tests/integration/ci_matrix.json

@@ -0,0 +1,12 @@
+{
+  "default": [
+    {"suite": "base", "setup": "ollama"},
+    {"suite": "vision", "setup": "ollama-vision"},
+    {"suite": "responses", "setup": "gpt"}
+  ],
+  "schedules": {
+    "1 0 * * 0": [
+      {"suite": "base", "setup": "vllm"}
+    ]
+  }
+}