fix(discover) Honor discover2.tags_facet_enable_sampling when applying sampling (#19883)
fix(discover) Honor discover2.tags_facet_enable_sampling when applying sampling (#19883)

Depends on https://github.com/getsentry/sentry/pull/19882

The transactions table only included the sampling key clause in april (for on prem). There is no possible migration there without migrating to a new table. People may have already created that table and there is no support for data migrations in snuba yet.
If we start having users using tracing/preformance on prem, who created the table long before that they may run into troubles when they have enough data in the transactions table to trigger the sampling rate.
Snuba would reject those queries.

This honors the flag introduced in https://github.com/getsentry/sentry/pull/19882
beeftornado/sentry,beeftornado/sentry,beeftornado/sentry