Fix sentry cookbook so it doesn't reinstall deprecated pip modules
As per https://gitlab.com/gitlab-com/infrastructure/issues/2160 we need to change https://dev.gitlab.org/cookbooks/gitlab-sentry so it doesn't reinstall sentry-gitlab
and sentry-slack
pip modules, which are not supported anymore on sentry.
Also update supervisor-sentry-conf.erb
file to log to a file.