freedreno/ci: add prefix for a630-vk-asan tests
Follow up from the prefix issue raised in MR !31916 (merged) for a630-gles-asan
Do the same thing for job a630-vk-asan
which simplifies the ci without any substantive changes:
Before example: https://gitlab.freedesktop.org/mesa/mesa/-/jobs/66094236
After: https://gitlab.freedesktop.org/dbrouwer/mesa/-/jobs/66096374
Edited by Deborah Brouwer