fix(rocm): Rename tag suffix for hipblas whisper build to match backend config (#6247)

Rename tag suffix for hipblas whisper to match backend config

hipblas images generally have the suffix `-gpu-rocm-hipblas-X`. One exception to this currently is the hipblas build of Whisper which has the suffix `gpu-hipblas-whisper.

However, as `backend/index.yaml` references the image tag for Whisper using the more consistent form (i.e. `latest-gpu-rocm-hipblas-whisper`), it is not possible to add the backend as raised in #6114.

Therefore, rename the suffix for hipblas whisper images to use the more consistent form, aligning with other hipblas builds as well as the expected image name in `backend/index.yaml`.

Signed-off-by: Kingsley Jarrett <kj@kingj.net>