Update OSX persistent ccache to leverage new storage.

[ryanaslett]

MacStadium is deprecating the "shared VM storage" that comes with the Orka Cluster, and, as we have seen, has also caused us some issues in the past with NFS breaking.

I just got off a call with them and they've agreed to offer us another singular bare metal mac that we can use as a persistent node alongside our existing cluster where we can put our shared ccache.

There are a couple ways forward on this machine:

1. expose the drive as a network file share to the orka nodes that mount it as they come up so they access the cache via the filesystem
2. Install Redis/Valkey on the new node and use ccache's ability to leverage that.

My preference is 2, as Im suspicious of network filesystems, and I believe that a Redis/Valkey cache will be performant enough to satisfy our requirements.