Clean up unused variable QA_ISSUE_URL in pipeline

What does this MR do and why?

Describe in detail what your merge request does and why.

Almost exactly two years from today 😀 , the usage of QA_ISSUE_URL was removed from the code base of release-tools !1779 (merged). However, it is still mentioned in 2 jobs in the pipeline:

• https://gitlab.com/gitlab-org/release-tools/-/blob/new-release-environment-send-noti/.gitlab/ci/automation.gitlab-ci.yml#L136
• https://gitlab.com/gitlab-org/release-tools/-/blob/new-release-environment-send-noti/.gitlab/ci/automation.gitlab-ci.yml#L105

Currently, it doesn't break anything, but it create some confusion when we see errors in the job log: ERROR: No files to upload (e.g. https://ops.gitlab.net/gitlab-org/release/tools/-/jobs/13630626#L128). Thus, if it is unused, we should remove it completely.

Close gitlab-com/gl-infra/delivery#20171 (closed)

Content

• Clean up unused variable QA_ISSUE_URL in pipeline

Author Check-list

• Has documentation been updated?