[ROCm] explicitly embed version within image name (#39735)
Summary:
This commit also removes the clang7 install for ROCm images, and properly cleans up the apt cache after ROCm installation to reduce image sizes.
Embedding the ROCm version within the image name follows the precedent set by CUDA images and decouples image creation from ROCm implicitly installing the latest version when images are prepared.
CC sunway513 ezyang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39735
Differential Revision: D21976162
Pulled By: ezyang
fbshipit-source-id: 9801106e8cb118a812113ec077154e72a9c2eb2d
