This fixes the Spring version mismatch between flow-server-3.0-SNAPSHOT and vaadin-spring-13.0-SNAPSHOT.
Also removes the workaround added to avoid a runtime failure caused by the version mismatch (added in #7024).

This fixes the Spring version mismatch between flow-server and the flow-ccdm-connect test.
Also remove the dependency to `vaadin-spring` to break the circular dependency.

There is a separate task to remove the dependency later: #7030