Merge pull request #60053 from rkachach/fix_issue_68315

mgr/cephadm: move Grafana's subpath handling logic to grafan config

Reviewed-by: Adam King <adking@redhat.com>
Reviewed-by: Ernesto Puerta <epuertat@redhat.com>
Reviewed-by: Nizamudeen A <nia@redhat.com>

diff --cc src/pybind/mgr/cephadm/templates/services/mgmt-gateway/external_server.conf.j2
Simple merge

diff --cc src/pybind/mgr/cephadm/tests/test_services.py
Simple merge