We work at a computer company. Let's use our computers (#1029)

Presently there is a shortage of servers to run Buildomat workers for CI
jobs. Fortunately, we work at a company that makes servers. So we can
just make more servers. And then we can use those servers for CI. And
then everyone's happy.

In order to do that, we must use the `lab-2.0-gimlet` Buildomat target
rather than `helios-2.0` or `lab-2.0-opte` targets. It's possible that
some or all of Omicron's CI cannot easily do that due to special-cased
behavior for the `i86pc` architecture to detect running in a dev
environment. Luckily, no such behavior exists in Propolis, so
we can just switch our Buildomat jobs to the `lab-2.0-gimlet` target 
and it will (mostly) Just Work. This way, we're not competing with
Omicron builds for the relatively scarce non-Gimlet workers.

One change to the `run_phd_with_args.sh` was required to make it
compatible with the `lab-2.0-gimlet` target. Previously, that script
hard-coded the names of disks on the `lab-2.0-opte` workers, which
don't exist on the Gimlet workers. Instead, since the names of disks
on the Gimlet workers include the SSD's WWN, we must use 
`pilot local disk list` to list all the U.2 devices at runtime, and use
them when creating the zpool. Note that this does now tie that script
to the Gimlet workers, but...that's fine, since the previous version
only worked on the non-Gimlet lab workers.

Author: hawkw

.github/buildomat/jobs/phd-run-migrate-from-base.sh

@@ -2,7 +2,7 @@
 #:
 #: name = "phd-run-migrate-from-base"
 #: variety = "basic"
-#: target = "lab-2.0-opte"
+#: target = "lab-2.0-gimlet"
 #: output_rules = [
 #:	"/tmp/phd-runner.log",
 #:	"/tmp/phd-tmp-files.tar.gz",

.github/buildomat/jobs/phd-run.sh

@@ -2,7 +2,7 @@
 #:
 #: name = "phd-run"
 #: variety = "basic"
-#: target = "lab-2.0-opte"
+#: target = "lab-2.0-gimlet"
 #: output_rules = [
 #:	"/tmp/phd-runner.log",
 #:	"/tmp/phd-tmp-files.tar.gz",

.github/buildomat/phd-run-with-args.sh

@@ -13,7 +13,11 @@ phddir="$PWD/phd-test"
 
 # Put artifacts on the runner's SSDs (the /work ramdisk is small by design, too
 # small for images of any appreciable size).
-pfexec zpool create -f phd-artifacts c1t1d0 c2t1d0
+
+# Find usable disks to make a zpool on. Note that this only works on Oxide
+# compute sled runners such as `lab-2.0-gimlet`.
+disks=( $(pilot local disk list -H -o type,disk | grep -v 'M.2' | cut -f 2) )
+pfexec zpool create -f phd-artifacts ${disks[@]}
 artifactdir="/phd-artifacts"
 
 banner 'Inputs'