build: kernel: Do not expect a modules tarball for vanilla kernel

When I added this I had in mind the period that we still relied on the
SEV module being generated, which we don't do for quite a long time.

This wrong assumption caused the cache to **ALWAYS** fail, increasing
our build time considerably for no reason.

Signed-off-by: Fabiano Fidêncio <ffidencio@nvidia.com>

.github/workflows/build-kata-static-tarball-amd64.yaml

@@ -143,7 +143,7 @@ jobs:
           if-no-files-found: error
 
       - name: store-extratarballs-artifact ${{ matrix.asset }}
-        if: ${{ matrix.asset == 'kernel' || startsWith(matrix.asset, 'kernel-nvidia-gpu') }}
+        if: ${{ startsWith(matrix.asset, 'kernel-nvidia-gpu') }}
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: kata-artifacts-amd64-${{ matrix.asset }}-modules${{ inputs.tarball-suffix }}
@@ -235,7 +235,6 @@ jobs:
         asset:
           - busybox
           - coco-guest-components
-          - kernel-modules
           - kernel-nvidia-gpu-modules
           - pause-image
     steps:

.github/workflows/build-kata-static-tarball-s390x.yaml

@@ -120,15 +120,6 @@ jobs:
           retention-days: 15
           if-no-files-found: error
 
-      - name: store-extratarballs-artifact ${{ matrix.asset }}
-        if: ${{ matrix.asset == 'kernel' }}
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
-        with:
-          name: kata-artifacts-s390x-${{ matrix.asset }}-modules${{ inputs.tarball-suffix }}
-          path: kata-build/kata-static-${{ matrix.asset }}-modules.tar.zst
-          retention-days: 15
-          if-no-files-found: error
-
   build-asset-rootfs:
     name: build-asset-rootfs
     runs-on: s390x