0.44.1 causes OOM errors for ads v7

[busunkim96]

See cl/370989216

This version of gapic-generator-python appears to have a memory leak and doesn't work with the googleads v7 protos. This causes the python microgenerator job to run for ~1 hours and then die with an OOM error. Can also reproduce the unbounded runtime / memory growth locally on glinux. We need to roll this back to 44.0 so the ads libraries can build.