Send SIGINT instead of SIGQUIT to puma

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

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done