- The query needs to be executed for hitting `select_all` so made sure
that query gets executed.
- Also instead of changing instance variable, just add new
configuration for prepared_statements: false and use it for this
test.
- This way we don't have to touch the internals of AR code and still
disable prepared statements config for this test.
Sets the connection collation to the database collation configured
in database.yml. Otherwise, `SET NAMES utf8mb4` will use the default
collation for that charset (utf8mb4_general_ci) when you may have chosen
a different collation, like utf8mb4_unicode_ci.
This only applies to literal string comparisons, not column values, so
it is unlikely to affect you.
