Doc updates to address downstream build issues

The following updates are required to address build errors or content discrepancies downstream.

mysql.adoc

• Update link target on L 2837 to xref:#mysql-transaction-metadata DONE
• append leveloffset attribute to include statement on L2310 DONE
  • include::../../partials/modules/all-connectors/proc-verifying-the-connector-deployment.adoc[leveloffset=+1]

oracle.adoc

• L49 Remove duplicate closing block delimiter (====) DONE
• L60-61 Delete entries commented entries from list DONE

outbox-event-router.adoc

Per the proposal from gmorling@redhat.com on 18 Jan, because we still lack some basic vetting by QE, for in the downstream docs for Q1, we should adhere to the following guidelines:

The outbox event router is marked as TP.
The note on binary (Avro) messages should be brought back; I think
we're ready to support it as TP as of 1.7 and as GA as of 1.8

I'll make the following updates:

• L29 Insert TP statement that is conditionalized for product. DONE
• L41 Insert list entry for * xref:options-for-applying-the-outbox-event-router-transformation-selectively DONE
• L49 Insert list entry for * xref:expanding-escaped-json-string-as-json[] DONE
• L201,241 Remove community conditional around Using Avro topic and add TP abbreviated statement DONE

I've applied another set of fixes directly to 1.7. Those were previously applied to main, but were never backported to 1.7.