alpine-based image does not honor use_curl_http_client

[ploxiln]

This seems to be because the alpine-based image uses a supervisor.conf which has command=python agent/ddagent.py --use_simple_http_client=1 while the debian-based image uses a supervisor.conf which does not have the flag --use_simple_http_client=1. There are a lot supervisor.conf out there and I'm not sure what the logic is which chooses one, but this is the only one which has that flag:
https://github.com/DataDog/dd-agent/blob/9ba3551885139490c834033716987b948fa0a19d/packaging/datadog-agent/source/supervisor.conf#L28

After I manually edited /opt/datadog-agent/agent/supervisor.conf in the alpine-based container to not include that flag, it started working. (It was previously getting the mysterious instant 599 "Network Unreachable" errors with the tornado simple http client. I wonder if that's because curl implements "happy eyeballs" and tries ipv4 after 3 ipv6 addresses fail to be route-able.)

I'm testing with datadog/docker-dd-agent:12.4.5181 and datadog/docker-dd-agent:12.4.5181-alpine