Truncate output that we log from commands to 10 lines (#9286)

Make output nicer and add first/last 10 lines

Log correct string

Author: ericholscher

readthedocs/doc_builder/environments.py

@@ -455,11 +455,16 @@ def run_command_class(
 
         if build_cmd.failed:
             if warn_only:
-                msg = 'Command {cmd} failed'.format(cmd=build_cmd.get_command())
+                msg = "Command failed"
+                build_output = ""
                 if build_cmd.output:
-                    msg += ':\n{out}'.format(out=build_cmd.output)
+                    build_output += "\n".join(build_cmd.output.split("\n")[10:])
+                    build_output += "\n ..Output Truncated.."
+                    build_output += "\n".join(build_cmd.output.split("\n")[:10])
                 log.warning(
                     msg,
+                    command=build_cmd.get_command(),
+                    output=build_output,
                     project_slug=self.project.slug if self.project else '',
                     version_slug=self.version.slug if self.version else '',
                 )