Remove st2resultstracker from the Docker

Remove st2resultstracker service from the packaging & startup logic as it's not needed since st2 `v3.3.0` due to mistral removal.
See https://github.com/StackStorm/st2/issues/5070 for more context.

This should be easy & fun task, if anyone from @StackStorm/contributors wants to help removing that.