Backport PR #17458 due to conflict.
Why I did it
Optimize syslog rate limit feature for fast and warm boot
Work item tracking
Microsoft ADO (number only):
How I did it
Optimize redis start time
Don't render rsyslog.conf in container startup script
Disable containercfgd by default. There is a new CLI to enable it (in another PR)
How to verify it
Manual test
Regression test
* Build a Docker base image based on Debian Stretch
* Build a config-engine Docker image based on Stretch
* Do not install socat from Debian repo
* Add changes that were made to docker-base since this PR was opened
