mgr/dashboard: Disable TLS 1.0 and 1.1

mgr/dashboard: Disable TLS 1.0 and 1.1

Disable these TLS versions because of security issues.

Fixes: https://tracker.ceph.com/issues/48360
Signed-off-by: Volker Theile <vtheile@suse.com>
(cherry picked from commit 5cf222b6d2a5cdc7ff23357b12878d34a4e68801)

Conflicts:
- src/pybind/mgr/dashboard/module.py
Limiting TLS version seems to work only with CherryPy >= 8.9.1 (Ubuntu 18.04 or SUSE Leap 15.1) based on tests in Teuthology. It failed on Ubuntu 16.04 (CherryPy 3.5.0) and RHEL 7.9 (CherryPy 3.2.2).
- qa/tasks/mgr/test_dashboard.py
Tests must be removed because they will not work in Teuthology because of outdated cherrypy versions on most platforms. Only Ubuntu 18.04 (and downstream SUSE Leap 15.1) will work, but it's not possible to limit QA runs to that specific platforms.