Disable issue trackers in Security Products projects

Description

Following this week's ~"Security Products" meeting, we decided to remove restrict the usage of the issue trackers from all our sub-projects, and use this tracker instead. It will be less confusing for users, who are opening issues there, often duplicating some from EE tracker.

Proposal

• update projects setting to set Issues Permissions to Only project members
• update projects settings to set the default issue template to leverage quick action to set our label:

/label ~"Security Products"

• update the CONTRIBUTING files to reflect this change, and invite the users to open issues here, with the ~"Security Products" label.