Summary:
Now that certmgr is gone, and direct mode is deprecated, we don't need
to assign DNS names or SSL certs to clusters. Remove dnsmgr.
Note: skaffold won't remove the dnsmgr deployment, that will need to be cleaned
manually on release.

Test Plan: skaffold a dev cloud, deploy a vizier to it

Reviewers: michelle, philkuz

Reviewed By: michelle

JIRA Issues: PP-3335
Signed-off-by: Vihang Mehta <vihang@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D11226

GitOrigin-RevId: 31c9946df47575fc07fe8fe693af6d25ec135d1f