adodbapi: Remove redundant `str` and `repr` calls, preferring `!r` formatting marker

[Avasam]

Adodbapi version of #2272

As title says:

• prefer more succint {!r} over repr
• avoid unnecessary calls to str() and repr()

Expecting a few slight behaviour changes: " vs ' in some strings where it should not matter, especially in traces, logs, debugging, tests, etc.