Release-tools fails to create a new security issue when milestones do not exist

Problem Statement

Rake task security:tracking_issue fails to create the next security release issue when the next milestone it's looking for is unable to be found. This is a problem when we are crossing major release breakpoints in our yearly cycle.

Example job: https://ops.gitlab.net/gitlab-org/release/tools/-/jobs/4003501

Milestone 13.13 does not exist, nor does milestone 13.14. This is expected as the plan for us this year was to go to version 14 after 13.12 was released.

Utilize this issue to figure out how to make release tools smarter. Milestone 14 already exists, so perhaps if a milestone is unable to be found, we can look ahead?