cephadm: keep mgr ports in sync when modules are enabled/disabled

cephadm: keep mgr ports in sync when modules are enabled/disabled

ceph orch ps  - was showing stale or incorrect port information for `mgr` daemons after enabling or disabling mgr modules (e.g., dashboard, prometheus).
This fix ensures the displayed ports always reflect the actual active module endpoints.

Code Fixes:
-----------
Changes in src/pybind/mgr/cephadm/services/cephadmservice.py:
- Extract and refactor _get_mgr_service_ports:
	The logic for reading active mgr module ports was inline inside prepare_create, using check_mon_command({'prefix': 'mgr services'}). It was extracted into a static helper method and refactored to read directly from mgr.get('mgr_map')['services'] instead -- which is faster and consistent with how get_dependencies reads the same data. The method is now shared by both prepare_create (existing use) and get_dependencies (new use).

- Extract `_get_mgr_service_ports`:
	The logic for reading active mgr module ports from `mgr_map['services']` was inline inside `prepare_create`. It was extracted into a static helper method so it can be reused by both `prepare_create` (existing use) and `get_dependencies` (new use). Returns the port numbers currently registered by active mgr modules (e.g., `[8443, 9283]`).

-  Override `get_dependencies` in `MgrService`:
	The base class returns `[]` for all Ceph daemons. The serve loop compares `get_dependencies()` output against `last_deps` (saved after the previous reconfig). If they differ, a reconfig is triggered. By overriding this method in `MgrService`, we make the serve loop aware of mgr port changes. Returns a sorted list such as `['port:8443', 'port:9283', 'sd_port:8765']`.

- Override `generate_config` in `MgrService`:
	After a reconfig completes, the result of `generate_config` is saved as `last_deps`. The inherited implementation returns `[]` as deps. If `[]` is saved but `get_dependencies` returns `['port:8443', 'sd_port:8765']`, they would always differ, causing an infinite reconfig loop. This override ensures that what is saved as `last_deps` matches what `get_dependencies` will return in the next iteration.

Changes in `src/pybind/mgr/cephadm/serve.py`:

- Update mgr cache on reconfig:
	The existing logic skipped the cache update for all Ceph daemon reconfigs. A new `elif` branch for mgr reconfigs fetches the existing cached `DaemonDescription`, updates only its `ports` field, and saves it back. This makes `ceph orch ps` reflect the correct ports immediately after a reconfig, without showing a misleading "starting" status.

Changes in `src/cephadm/cephadm.py`:

- Update `unit.meta` on reconfig:
	`unit.meta` is a per-daemon file on the host that stores metadata including ports.  It is read periodically by `cephadm ls` and fed back into the orchestrator cache. Previously it was only written on initial deployment, so every periodic cache refresh would overwrite the corrected ports with stale data from `unit.meta`. This change updates the `ports` field in `unit.meta` during reconfig, ensuring the cache refresh confirms the correct state rather than reverting it.

Changes to src/pybind/mgr/cephadm/tests/services/test_mgr.py:

- Updated _prepare helper:
	The original mocked check_mon_command to feed services data to prepare_create. Since our _get_mgr_service_ports now reads from mgr.get('mgr_map') instead of check_mon_command, the mock was replaced with mock_store_set('_ceph_get', 'mgr_map', ...) which sets the data in the right place.

- Added test_get_dependencies_changes_when_module_enabled:
   A new test that verifies get_dependencies returns different dep strings before and after a module is enabled. This directly tests the core sync mechanism -- the serve loop compares get_dependencies output against last_deps to detect port changes and trigger a reconfig.

to run new tests:
cd src/pybind/mgr
tox -e py3 -- cephadm/tests/services/test_mgr.py -v

Fixes: https://tracker.ceph.com/issues/76565
Signed-off-by: Yael Azulay <yazulay@redhat.com>