Drop unnecessary command from CLI plug-in (#3551)

The CLI plug-in stays up even without command. This saves a few
kilobytes of RAM.

It also allows s6-overlay's stage2 to complete. The stage2 execlineb
process has an enormously long cmdline, with strings like "init-stage2
failed" in it. This has previously led people to belive that there is a
problem (while there isn't). So as a side effect, getting stage2 to
complete side steps such confusion and makes the list of processes
cleaner.

supervisor/docker/cli.py

@@ -38,7 +38,6 @@ class DockerCli(DockerInterface, CoreSysAttributes):
         docker_container = self.sys_docker.run(
             self.image,
             entrypoint=["/init"],
-            command=["/bin/bash", "-c", "sleep infinity"],
             tag=str(self.sys_plugins.cli.version),
             init=False,
             ipv4=self.sys_docker.network.cli,