refactor: clean up unused variables in engine module
Removed unused variables to improve code clarity and maintainability. This change simplifies logic in `base.py`, `default.py`, and `result.py`. No functionality was altered.
Closes: #12535
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/12535
Pull-request-sha:
a9d849f3a4f3abe9aff49279c4cc81aa26aeaa9b
Change-Id: If78b18dbd33733c631f8b5aad7d55261fbc4817b
(cherry picked from commit
d1d81f80a3764e3ebc38481fb6fd82cf6295dcf9)
(cherry picked from commit
ba433ff9f567b0c58f5f78c2d5cf262f9e5e9c43)