Allow the kwargs for dbapi connections to inlcude a logger, and use this as the logger for the database that is used.

Also set a default logger that only logs at WARN level for the mock server tests to stop them from spamming the test log with a bunch of "Created multiplexed session." messages that are logged at INFO level.

Also removes some additional log spamming from the request-id tests.

The Emulator returns an empty pre-commit token when a commit is attempted
without a pre-commit token. This is different from not returning any
pre-commit token at all. The check for 'did the Commit return a pre-commit
token?' did not take this into account, which caused commits on the
Emulator that needed to be retried, not to be retried. This again caused
multiple test errors when running on the Emulator, as this would keep a
transaction present on the test database on the Emulator, and the Emulator
only supports one transaction at a time. These test failures went unnoticed,
because the test configuration for the Emulator had pinned the Emulator
version to 1.5.37, which did not support multiplexed sessions. This again
caused the tests to fall back to using regular sessions.

This change fixes the check for whether a pre-commit token was returned by
a Commit. It also unpins the Emulator version for the system tests using
default settings. This ensures that the tests actually use multiplexed
sessions.

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>