ceph-mgr crashes with the error: "cherrypy._cperror.NotFound" and "FileNotFoundError" for prometheus_receiver

Issue

• ceph-mgr crashes with the error: cherrypy._cperror.NotFound and FileNotFoundError for prometheus_receiver.

• ceph-mgr crashes with the below error:

  Internal Server Error
  Traceback (most recent call last):
  File "/lib/python3.6/site-packages/cherrypy/lib/static.py", line 58, in serve_file
      st = os.stat(path)
  FileNotFoundError: [Errno 2] No such file or directory: '/usr/share/ceph/mgr/dashboard/frontend/dist/en-US/prometheus_receiver'
  

• While handling of the above exception, getting the below traceback :

  Traceback (most recent call last):
   File "/usr/share/ceph/mgr/dashboard/services/exception.py", line 46, in dashboard_exception_handler
     return handler(*args, **kwargs)
   File "/lib/python3.6/site-packages/cherrypy/_cpdispatch.py", line 54, in __call__
         return self.callable(*self.args, **self.kwargs)
    File "/usr/share/ceph/mgr/dashboard/controllers/home.py", line 135, in __call__
         return serve_file(full_path)
    File "/lib/python3.6/site-packages/cherrypy/lib/static.py", line 65, in serve_file
         raise cherrypy.NotFound()
  cherrypy._cperror.NotFound: (404, "The path '/prometheus_receiver' was not found.")
  

• alertmanager is reporting the below error:

  May 16 09:49:54 node1.sample.com conmon[153583]: level=error ts=2022-05-16T09:49:54.466Z caller=dispatch.go:309 component=dispatcher msg="Notify for alerts failed" num_alerts=1 err="ceph-dashboard/webhook[0]: notify retry canceled due to unrecoverable error after 1 attempts: unexpected status code 404: https://192.168.0.81:8443//api/prometheus_receiver"