Remove additionalProperties: false from JDBC destination connectors

[grishick]

Problem

As discovered in https://github.com/airbytehq/oncall/issues/289, a spec declaring "additionalProperties": false introduces the risk of accidental breaking changes. Specifically, when removing a property from the spec, existing connector configs will no longer be valid.

To make these upgrades/rollbacks smoother, we need to remove additionalProperties from connectors affected by these changes.

Action items

• remove additionalProperties:false (or replace it with additionalProperties:true, whichever is the correct approach)
• publish new versions of JDBC-based connectors
• merge changes