Remove dependency local image

Tagging is necessary when building for single arch because there may be
nothing in cache yet.

Removing the image is necessary for multipaltform build because
local docker image store can only tag one arch. All per-arch build
results are still in cache from the single arch build.

Removing twice, which happens only for release pushing, was failing.

So, hoist removal out.

.github/workflows/build-ruby.yml

@@ -421,6 +421,10 @@ jobs:
           docker buildx build ${{ steps.vars.outputs.SRC }} "${cache_from[@]}" --output=type=image,push=true --build-arg BUILDKIT_INLINE_CACHE=1 --platform ${{ steps.vars.outputs.DOCKER_PLATFORMS }} -f ${{ steps.vars.outputs.DOCKERFILE }} --tag ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}-gcc
 
       # TODO: hardcoded musl, unify gnu instead
+      - name: Remove dependency local image (${{ join(matrix.arch, ', ') }})
+        if: ${{ matrix.libc == 'musl' }}
+        run: |
+          docker image rm ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}
       - name: Push commit compiler image (${{ join(matrix.arch, ', ') }})
         if: ${{ matrix.libc == 'musl' }}
         run: |
@@ -432,7 +436,6 @@ jobs:
           done
           cache_from+=(--cache-from=type=registry,ref=${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}-gcc)
           cache_from+=(--cache-from=type=registry,ref=${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }})
-          docker image rm ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}
           docker buildx build ${{ steps.vars.outputs.SRC }} "${cache_from[@]}" --output=type=image,push=true --build-arg BUILDKIT_INLINE_CACHE=1 --platform ${{ steps.vars.outputs.DOCKER_PLATFORMS }} -f ${{ steps.vars.outputs.DOCKERFILE }}.gcc --tag ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}-gcc-g${{ github.sha }}
       - name: Push release compiler image (${{ join(matrix.arch, ', ') }})
         if: ${{ inputs.push && matrix.libc == 'musl' }}
@@ -445,5 +448,4 @@ jobs:
           done
           cache_from+=(--cache-from=type=registry,ref=${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}-gcc)
           cache_from+=(--cache-from=type=registry,ref=${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }})
-          docker image rm ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}
           docker buildx build ${{ steps.vars.outputs.SRC }} "${cache_from[@]}" --output=type=image,push=true --build-arg BUILDKIT_INLINE_CACHE=1 --platform ${{ steps.vars.outputs.DOCKER_PLATFORMS }} -f ${{ steps.vars.outputs.DOCKERFILE }}.gcc --tag ${{ steps.vars.outputs.IMAGE }}:${{ steps.vars.outputs.RELEASE_TAG }}-gcc