[3.9] Docstring: replace pysqlite with sqlite3 (GH-31758) (GH-31778)

Replace two instances of "pysqlite" with "sqlite3" in sqlite3
docstrings. Also reword "is a no-op" to "does nothing" for clarity..
(cherry picked from commit b33a1ae7)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>