Update metrics.py

[vidartf]

I think this fixes an incorrect import?

[vidartf]

Cleanup after #97, xref #96.

[kevin-bates]

Hi @vidartf - thanks for looking into this.

I think the actual change relative to this file is to remove it altogether since it was moved from here into prometheus/log_functions.py in this change: jupyter/notebook@03e5dc0 and is no longer present in this location within Notebook.

And then apply this commit jupyter/notebook@7bc7df4 to prometheus/log_functions.py as it appears the cherry-pick for this commit was applied to the "pre-moved" metrics.py instead of prometheus/log_functions.py.

I think this would explain why the tests (relative to Batch-3) are passing and we're not getting failure on the change you proposed - which the correct fix otherwise.

Would you mind updating this PR to delete jupyter_server/metrics.py and apply the import update to juptyer_server/prometheus/log_functions.py?

[vidartf]

Cleaned up

[kevin-bates]

LGTM - thanks Vidar!