ref(ci): Do not send transactions from pytest-sentry (#41640)
Our developers are not using transactions or tracing for tests right
now, since we use `pytest-sentry` just to report flakey and broken
tests.
Transactions sent from `pytest-sentry` frequently run into rate limits
and create the second highest transaction volume in the sentry
organization. Since we do not need them at all, we can disable them
until there's more use for them.