fix(parser): only keep final traceback for each failing test

The Tempest report parser was updated to correctly extract the final traceback
when multiple tracebacks are present in a single log entry.

Previously, the parser would capture the first traceback encountered. This could lead to large amount of
inputs that our model can't handle. For now let's just focus on the last
traceback that is found for each test.

Author: EmilienM

src/rca_accelerator_chatbot/api.py

@@ -175,8 +175,9 @@ def _extract_test_name(test_name_part: str) -> str:
     return test_name
 
 
-async def fetch_and_parse_tempest_report(url: str) -> List[Dict[str, str]]:
-    """Fetches and parses the Tempest HTML report to extract test names and tracebacks."""
+async def fetch_and_parse_tempest_report(url: str) -> List[Dict[str, str]]: # pylint: disable=too-many-locals
+    """Fetches and parses the Tempest HTML report to extract test names
+    and the last traceback for each failed test."""
     async with httpx.AsyncClient(verify=False, follow_redirects=True) as client:
         try:
             response = await client.get(url, auth=HTTPSPNEGOAuth(mutual_authentication=OPTIONAL))
@@ -202,14 +203,20 @@ async def fetch_and_parse_tempest_report(url: str) -> List[Dict[str, str]]:
             test_name_part = row_text[:traceback_start_index].strip()
             test_name = _extract_test_name(test_name_part)
 
-            traceback_text = row_text[traceback_start_index:]
-            end_marker_index = traceback_text.find("}}}")
-            if end_marker_index != -1:
-                traceback_text = traceback_text[:end_marker_index].strip()
-            else:
-                traceback_text = traceback_text.strip()
-
-            results.append({"test_name": test_name, "traceback": traceback_text})
+            tb_marker = "Traceback (most recent call last):"
+            traceback_pattern = re.compile(
+                # Match from one tb_marker to the next (non-greedy), or to end of string
+                f"{re.escape(tb_marker)}.*?(?={re.escape(tb_marker)}|$)",
+                re.DOTALL
+            )
+
+            traceback_parts = traceback_pattern.findall(row_text[traceback_start_index:])
+            if traceback_parts:
+                last_traceback = traceback_parts[-1].strip()
+                end_marker_index = last_traceback.find("}}}")
+                if end_marker_index != -1:
+                    last_traceback = last_traceback[:end_marker_index].strip()
+                results.append({"test_name": test_name, "traceback": last_traceback})
 
     if not results:
         pass