Add CDC enabled sanity check [DBZ-6750]

Migrated from [DBZ-6750](https://issues.redhat.com/browse/DBZ-6750)

In SQL Server we build a cache of capture tables and references to tables that have CDC enabled; however if a user mistakenly disables CDC on the table, the connector continues to run without reporting any form of error or problem.

We should think about adding a sanity check that can either be an opt-in feature that runs on each iteration of the polling loop or on a set interval that determines whether a given table that was previously CDC enabled is no longer enabled and assert.

See conversation from Zulip:
https://debezium.zulipchat.com/#narrow/stream/348252-community-sqlserver/topic/when.20does.20Debezium.20realize.20CDC.20is.20not.20enabled.3F/near/381289274

The issue identifies the SQL Server connector's CDC capture-table cache and polling loop as the relevant entry points; start by locating those components and review the linked DBZ-6750 issue and Zulip discussion. Done means the connector detects when a previously CDC-enabled table is disabled and reports the problem, with the polling or interval behavior selected.

Written by the indexing model from the issue text.