grow disks on ci-runner-x86-03

ci-runner-x86-03 is one of our biggest and strongest runners: it has 80 cores and 1.5TB of RAM!

yet it only has 1TB of (SDD) disk space, which now seems rather small. we seem to keep running out of disk space on the thing (#42272 (closed)), so we should just throw hardware at this problem to sweep it under the rug a little longer.

as a reference, here's the different disk allocations of the various runners:

• ci-runner-x86-02: 300G SSD (?) VM on gnt-dal, some room available?
• ci-runner-x86-03: 2x1TB SSD (1TB total), 575G for /srv 245G for /srv/shadow, no expansion room available
• ci-runner-x86-14: 4x1.7TB NVMe SSD, + 2x1TB NVMe SSD so ~4.4TB possible after RAID, currently only 1.7TB allocated, unused

so i think we should at least double the capacity of -03. it will surpass the capacity of -02 which could then run out of space, but we could easily retire that runner if we can steal some time off the (unused) -14 runner.

the task here is to look at the (peculiar) server hardware (this is the old Dell server donated by cymru, i believe) and see what kind of drives we could use, how much they would cost, and whether we need approval.

i think that, with the new handbook, as a team lead, i can approve modest expenses here.