Remove invalid database check in _bulkcopy

Co-authored-by: saurabh500 <1623701+saurabh500@users.noreply.github.com>

Author: Copilot

mssql_python/cursor.py

@@ -2627,12 +2627,6 @@ def _bulkcopy(
         if not params.get("server"):
             raise ValueError("SERVER parameter is required in connection string")
 
-        if not params.get("database"):
-            raise ValueError(
-                "DATABASE parameter is required in connection string for bulk copy. "
-                "Specify the target database explicitly to avoid accidentally writing to system databases."
-            )
-
         # Translate parsed connection string into the dict py-core expects.
         pycore_context = connstr_to_pycore_params(params)