Send SIGINT instead of SIGQUIT to puma

Merged Jörg Behrmann requested to merge behrmann/gitlab:puma_sigterm into master

What does this MR do?

Instead of using SIGQUIT in bin/web_puma SIGINT is used instead, since Puma doesn't handle SIGQUIT as noted by @mphilipps in #299570 (closed), which on source installs leads to /etc/init.d/gitlab stop waiting forever.

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Edited by Jörg Behrmann