mgr/dashboard: don't log tracebacks on 404s

[epuertat]

Currently we're logging tracebacks on expected request errors as 404,
401, etc. This may cause confusion to users, which might think that
something really wrong was happening there.

This should be extended to many DashboardExceptions that simply return
expected HTTP error codes (403, 415, 3xx, etc).

Before

2022-06-29T18:16:09.360+0000 7f6cdb6a9700  0 [dashboard DEBUG request] [::ffff:172.20.0.1:38320] [GET] [None] /invented_url
2022-06-29T18:16:09.361+0000 7f6cdb6a9700  0 [dashboard DEBUG controllers.home] frontend language from headers: ['en-us']
2022-06-29T18:16:09.361+0000 7f6cdb6a9700  0 [dashboard DEBUG controllers.home] found directory for language 'en-us'
2022-06-29T18:16:09.361+0000 7f6cdb6a9700  0 [dashboard DEBUG controllers.home] serving static content: /ceph/src/pybind/mgr/dashboard/frontend/dist/en-US/invented_url
2022-06-29T18:16:09.362+0000 7f6cdb6a9700  0 [dashboard ERROR exception] Internal Server Error
Traceback (most recent call last):
  File "/usr/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: '/ceph/src/pybind/mgr/dashboard/frontend/dist/en-US/invented_url'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/ceph/src/pybind/mgr/dashboard/services/exception.py", line 47, in dashboard_exception_handler
    return handler(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/cherrypy/_cpdispatch.py", line 54, in __call__
    return self.callable(*self.args, **self.kwargs)
  File "/ceph/src/pybind/mgr/dashboard/controllers/home.py", line 134, in __call__
    return serve_file(full_path)
  File "/usr/lib/python3.6/site-packages/cherrypy/lib/static.py", line 65, in serve_file
    raise cherrypy.NotFound()
cherrypy._cperror.NotFound: (404, "The path '/invented_url' was not found.")
2022-06-29T18:16:09.363+0000 7f6cdb6a9700  0 [dashboard INFO request] [::ffff:172.20.0.1:38320] [GET] [404] [0.173s] [1.8K] [4de1f6a2-8770-4e1c-87aa-6f5d5de3dca6] /invented_url

After

2022-06-29T18:15:02.002+0000 7f9c40007700  0 [dashboard DEBUG request] [::ffff:172.20.0.1:37596] [GET] [None] /invented_url
2022-06-29T18:15:02.002+0000 7f9c40007700  0 [dashboard DEBUG controllers.home] frontend language from headers: ['en-us']
2022-06-29T18:15:02.002+0000 7f9c40007700  0 [dashboard DEBUG controllers.home] found directory for language 'en-us'
2022-06-29T18:15:02.002+0000 7f9c40007700  0 [dashboard DEBUG controllers.home] serving static content: /ceph/src/pybind/mgr/dashboard/frontend/dist/en-US/invented_url

Fixes: https://tracker.ceph.com/issues/55720
Signed-off-by: Ernesto Puerta epuertat@redhat.com

Contribution Guidelines

• To sign and title your commits, please refer to Submitting Patches to Ceph.

• If you are submitting a fix for a stable branch (e.g. "pacific"), please refer to Submitting Patches to Ceph - Backports for the proper workflow.

Checklist

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  • References tracker ticket
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  • Affects Dashboard, opened tracker ticket
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