ci: Use ignore_scheduled_pipelines in .radeonsi-rules
Without this, scheduled pipelines erroneously tried to crate jobs using this template, which can't work, because dependency jobs don't exist in scheduled pipelines. Unfortunately, this resulted in scheduled pipelines not running silently, without any direct feedback about what's wrong.
Fixes: 6c8b9215 "ci: Build kernels and rootfs for x86 devices"
/cc @bentiss