Revert "PYTHON-2048 Improve error message for bulk_write failures due to unsu…"

This reverts commit 4470309fa0.

pymongo/bulk.py

@@ -149,19 +149,8 @@ def _merge_command(
 
 def _raise_bulk_write_error(full_result: _DocumentOut) -> NoReturn:
     """Raise a BulkWriteError from the full bulk api result."""
-    # retryWrites on MMAPv1 should raise an actionable error.
     if full_result["writeErrors"]:
         full_result["writeErrors"].sort(key=lambda error: error["index"])
-        err = full_result["writeErrors"][0]
-        code = err["code"]
-        msg = err["errmsg"]
-        if code == 20 and msg.startswith("Transaction numbers"):
-            errmsg = (
-                "This MongoDB deployment does not support "
-                "retryable writes. Please add retryWrites=false "
-                "to your connection string."
-            )
-            raise OperationFailure(errmsg, code, full_result)
     raise BulkWriteError(full_result)