Execute initial statements only once

Currently, this is baked right into the JdbcConnection#connection(boolean) method, i.e. bound directly to the lifecycle of the connection itself. This means this will be executed more often than needed or desirable, as really the semantics of this option should be "initial upon connector start-up". Hence this logic should be removed from there and rather be pulled into the change event source coordinator, as one of the initial tasks. Or the BaseSourceTask class perhaps.