Add chainsaw based test for DataPlaneClientCertificate managed by `KonnectExtension`

[pmalek]

Problem statement

#2631 introduced managed KongDataPlaneClientCertificate for KonnectExtensions.

This issue tracks adding a chainsaw based test when its machinery is in place

Depends on #2761

Acceptance criteria

• An e2e test using chainsaw is added. This test checks whether KongDataPlaneClientCertificate is properly provisioned for KonnectExtension.