As a result of dropping support for trusty, we can remove our old
pattern of putting `if False` before importing the typing module,
which was essential for Python 3.4 support, but not required and maybe
harmful on newer versions.
cron_file_helper
check_rabbitmq_consumers
hash_reqs
check_zephyr_mirror
check_personal_zephyr_mirrors
check_cron_file
zulip_tools
check_postgres_replication_lag
api_test_helpers
purge-old-deployments
setup_venv
node_cache
clean_venv_cache
clean_node_cache
clean_emoji_cache
pg_backup_and_purge
restore-backup
generate_secrets
zulip-ec2-configure-interfaces
diagnose
check_user_zephyr_mirror_liveness
Apparently, we were incorrectly expressing the paths in the
caches_in_use data structures for these two cache-cleaning algorithms,
resulting in the default threshhold_days algorithm controlling which
caches could be garbage-collected. While the emoji one was just a
performance optimization for upgrade-zulip-from-git, it was possible
for the main `node_modules` cache in use in production to be GCed,
resulting in LaTeX rendering being broken.
This saves about 400ms when running clean-unused-caches, basically by
calling its sub-rountines by import (rather than
`subprocess.check_call()`). The performance optimization seems well worth it.
Fixes#9766.