Remove pytest-mock dependency #717

Job	Run time
Test aip-encrypt on Firefox	19m 42s
Test aip-encrypt on Chrome	18m 38s
Test aip-encrypt-mirror on Firefox	13m 50s
Test aip-encrypt-mirror on Chrome	12m 40s
Test black-box on Chrome	29m 10s
Test icc on Firefox	13m 47s
Test icc on Chrome	13m 40s
Test ipc preservation on Firefox	18m 1s
Test ipc preservation on Chrome	17m 7s
Test ipc access on Firefox	17m 7s
Test ipc access on Chrome	15m 56s
Test man-norm on Firefox	11m 18s
Test man-norm on Chrome	11m 35s
Test metadata-xml on Firefox	19m 42s
Test metadata-xml on Chrome	17m 39s
Test tcc on Firefox	13m 42s
Test tcc on Chrome	13m 2s
Test tpc on Firefox	14m 11s
Test tpc on Chrome	12m 59s
Test uuids-dirs on Firefox	13m 29s
Test uuids-dirs on Chrome	12m 39s
	5h 29m 54s

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