Add partition_remove_hook logging and metrics

[dmitry-sinina]

We need to capture stdout and stderr streams of partition_remove_hook script https://github.com/yeti-switch/yeti-web/blob/master/app/jobs/jobs/partition_removing.rb#L53 to print them as yeti-scheduler logs

We need additional metrics:

ruby_yeti_partition_removing_hook_executions - counter that incrementing every script run
ruby_yeti_partition_removing_hook_duration - counter, aggregated duration of script executions
ruby_yeti_partition_removing_hook_errors - counter, incrementing when script failing