Revert "lima/ci: There is no need to redefine HWCI_TEST_SCRIPT"

.lava-test:arm64 defines HWCI_TEST_SCRIPT for deqp use. And .lava-meson-gxl-s805x-libretech-ac makes use of it. So revert this pre-holiday-rush-commit.

This reverts commit c16feac5.