automation: drop debian:11-riscv64 container

There are two reasons for that:
1. In the README, GCC baseline is chosen to be 12.2, whereas Debian 11
   uses GCC 10.2.1.
2. Xen requires mandatory some Z extensions, but GCC 10.2.1 does not
   support Z extensions in -march, causing the compilation to fail.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

automation/gitlab-ci/build.yaml

@@ -729,20 +729,6 @@ debian-12-ppc64le-gcc:
     HYPERVISOR_ONLY: y
 
 # RISC-V 64 cross-build
-debian-11-riscv64-gcc:
-  extends: .gcc-riscv64-cross-build
-  variables:
-    CONTAINER: debian:11-riscv64
-    KBUILD_DEFCONFIG: tiny64_defconfig
-    HYPERVISOR_ONLY: y
-
-debian-11-riscv64-gcc-debug:
-  extends: .gcc-riscv64-cross-build-debug
-  variables:
-    CONTAINER: debian:11-riscv64
-    KBUILD_DEFCONFIG: tiny64_defconfig
-    HYPERVISOR_ONLY: y
-
 debian-12-riscv64-gcc:
   extends: .gcc-riscv64-cross-build
   variables:

automation/scripts/containerize

@@ -31,7 +31,6 @@ case "_${CONTAINER}" in
     _fedora) CONTAINER="${BASE}/fedora:41-x86_64";;
     _bullseye-ppc64le) CONTAINER="${BASE}/debian:11-ppc64le" ;;
     _bookworm-ppc64le) CONTAINER="${BASE}/debian:12-ppc64le" ;;
-    _bullseye-riscv64) CONTAINER="${BASE}/debian:11-riscv64" ;;
     _bookworm-riscv64) CONTAINER="${BASE}/debian:12-riscv64" ;;
     _bookworm-x86_64-gcc-ibt) CONTAINER="${BASE}/debian:12-x86_64-gcc-ibt" ;;
     _bookworm|_bookworm-x86_64|_) CONTAINER="${BASE}/debian:12-x86_64" ;;