bci2: Allow jobs to choose if they run on an RPi

Jobs that need to compile code, as opposed to simply installing
prebuilt packages and/or copying in files, probably do not want to run
on a Raspberry Pi.  To allow such jobs to opt out of running on a Pi and
wait for the Cluster Autoscaler to bring up an aarch64 node in AWS, the
`buildContainerImage2` function now takes an optional `pi` argument.
The argument defaults to `true`, so existing jobs that expect to run on
a Pi will continue to do so.

resources/podTemplate2.yaml

@@ -17,7 +17,3 @@ spec:
       limits:
         github.com/fuse: 1
   hostUsers: false
-  tolerations:
-  - key: du5t1n.me/machine
-    value: raspberrypi
-    effect: NoExecute