Upgrade CI machines to have more RAM
Upgrade CI machines to have more RAM

The build seems to hang when executing NextPNR chip DB genrules, which
I've also seen happening on my laptop when I was low on RAM and it
started swap thrashing while making little progress. This upgrades from
7.2GB RAM to 28.8GB (there is no step between these two, Cloud Build
only supports 8 and 32 vCPU VMs beyond the low CPU default).

hdl/bazel_rules_hdl,hdl/bazel_rules_hdl,hdl/bazel_rules_hdl,hdl/bazel_rules_hdl