Merge branch '41293-fix-command-injection-vulnerability-on-system_hook_push-queue-through-web-hook' into 'security-10-3'

Don't allow line breaks on HTTP headers

See merge request gitlab/gitlabhq!2277

(cherry picked from commit 7fc0a6fc096768a5604d6dd24d7d952e53300c82)

073b8f9c Don't allow line breaks on HTTP headers