catch OSError (base of ConnectionError) and asyncpg errors for terminate

catch OSError (base of ConnectionError) and asyncpg errors for terminate

Fixed regression in the asyncpg dialect caused by :ticket:`10717` in
release 2.0.24 where the change that now attempts to gracefully close the
asyncpg connection before terminating would not fall back to
``terminate()`` for other potential connection-related exceptions other
than a timeout error, not taking into account cases where the graceful
``.close()`` attempt fails for other reasons such as connection errors.

Fixes: #10863
Change-Id: If1791bce26803f92547cdf26fb641996c7f638fa