Reliability reviews are performed by Scalability: Practices group

As readiness reviews are now reviewed by Scalability: Practices, the issue template should be updated to reflect this so the correct reviewers can be assigned. This MR updates the Reliability reviewer to direct team members to engage with Practices instead.

@kwanyangu - I linked to the Scalability: Practices handbook page so that team members know how best to engage Practices, however if you would like to have an issue template on the Practices tracking project used, similar to how InfraSec manages assigning team members for these reviews, I can update this MR to link to it. Also, if there is a better group to link to instead of the handbook page, please let me know, I'll update the MR. I checked this group however it also includes Engineering Managers from other parts of Scalability, so figured this was not the correct group to direct team members to for engaging with Practices.