time.clock has been deprecated and removed in python 3.8 in favor of time.perf_counter/process_time

[tirkarthi]

Description

time.clock has been deprecated and removed in python 3.8 in favor of time.perf_counter/process_time . Reference : python/cpython#13270

Steps to reproduce

synapse/logging/utils.py
88:        start = time.clock()
95:            end = time.clock()

[anoadragon453]

As mentioned in the attached PR (thanks!) it seems as if the method that calls time.clock in Synapse is no longer used.