Add auto-trigger constraints

[gazay]

We have leaking application, but it leaks just sometimes, maybe once a day.
And we don't really need to take metrics all the time.
We need to add some constraints in config, and check them every time trigger is called.

For example

Mnemonic.new do |config|
  config.run_if { rss > 10_000_000 && ObjectSpace.each_object(Sidekiq::Worker).count > 100 }
  ...
end