Replace `createFlash` with GlAlert in `ee/app/assets/javascripts/integrations/jira/issues_list/components/jira_issues_list_root.vue`

To support links in error messages (!66987 (comment 644747021)), as well as to conform to the design system, we should replace createFlash with GlAlert on the Jira Issues page.

Usage of createFlash: https://gitlab.com/gitlab-org/gitlab/blob/9c2bacff3dddea3d06a0cd3a84e15d5f3676b2c4/ee/app/assets/javascripts/integrations/jira/issues_list/components/jira_issues_list_root.vue#L171