chore(telemetry): truncate error stack traces and add error_type tag (#15149)

## Description

Reduce data sent to telemetry logs, making them easier to query. We
generally only need the last few frames anyways.

Adding an "error_type" tag will make it so we don't have to query the
error stack to group by the exception class name.

## Testing

<!-- Describe your testing strategy or note what tests are included -->

## Risks

<!-- Note any risks associated with this change, or "None" if no risks
-->

## Additional Notes

<!-- Any other information that would be helpful for reviewers -->

Author: brettlangdon

ddtrace/internal/telemetry/writer.py

@@ -433,10 +433,23 @@ def add_error_log(self, msg: str, exc: Union[BaseException, tuple, None]) -> Non
         if config.LOG_COLLECTION_ENABLED:
             stack_trace = None if exc is None else self._format_stack_trace(exc)
 
+            error_type = "unknown"
+            try:
+                if exc is not None:
+                    if isinstance(exc, tuple) and len(exc) == 3:
+                        error_type = exc[0].__name__
+                    else:
+                        error_type = type(exc).__name__
+            except Exception:
+                log.debug("Failed to extract error type from exception: %r", (exc,), exc_info=True)
+
             self.add_log(
                 TELEMETRY_LOG_LEVEL.ERROR,
                 msg,
                 stack_trace=stack_trace if stack_trace is not None else "",
+                tags={
+                    "error_type": error_type,
+                },
             )
 
     def _format_stack_trace(self, exc: Union[BaseException, tuple]) -> Optional[str]:
@@ -450,7 +463,8 @@ def _format_stack_trace(self, exc: Union[BaseException, tuple]) -> Optional[str]
 
         tb = traceback.extract_tb(exc_traceback)
         formatted_tb = ["Traceback (most recent call last):"]
-        for filename, lineno, funcname, srcline in tb:
+        # Only include the last 20 frames
+        for filename, lineno, funcname, srcline in tb[-20:]:
             if is_user_code(filename):
                 formatted_tb.append("  <REDACTED>")
                 formatted_tb.append("    <REDACTED>")

tests/telemetry/test_writer.py

@@ -995,6 +995,7 @@ def test_add_error_log(mock_time, telemetry_writer, test_agent_session):
         log_entry = logs[0]
         assert log_entry["level"] == TELEMETRY_LOG_LEVEL.ERROR.value
         assert log_entry["message"] == "Test error message"
+        assert log_entry["tags"] == "error_type:jsondecodeerror"
 
         stack_trace = log_entry["stack_trace"]
         expected_lines = [
@@ -1012,6 +1013,77 @@ def test_add_error_log(mock_time, telemetry_writer, test_agent_session):
             assert expected_line in stack_trace
 
 
+def test_add_error_log_large_stack(mock_time, telemetry_writer, test_agent_session):
+    """Test add_integration_error_log functionality with real stack trace"""
+    try:
+
+        def _(n):
+            if n == 200:
+                raise ValueError("Test exception for large stack trace")
+            return _(n + 1)
+
+        _(0)
+    except Exception as e:
+        telemetry_writer.add_error_log("Test error message", e)
+        telemetry_writer.periodic(force_flush=True)
+
+        log_events = test_agent_session.get_events("logs")
+        assert len(log_events) == 1
+
+        logs = log_events[0]["payload"]["logs"]
+        assert len(logs) == 1
+
+        log_entry = logs[0]
+        assert log_entry["level"] == TELEMETRY_LOG_LEVEL.ERROR.value
+        assert log_entry["message"] == "Test error message"
+        assert log_entry["tags"] == "error_type:valueerror"
+
+        stack_trace = log_entry["stack_trace"]
+        expected_lines = """Traceback (most recent call last):
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+  <REDACTED>
+    <REDACTED>
+builtins.ValueError: <REDACTED>"""
+        assert stack_trace == expected_lines
+
+
 def test_add_integration_error_log_with_log_collection_disabled(mock_time, telemetry_writer, test_agent_session):
     """Test that add_integration_error_log respects LOG_COLLECTION_ENABLED setting"""
     original_value = telemetry_config.LOG_COLLECTION_ENABLED