pw_env_setup: Retrieve ARM Mac LUCI packages
pw_env_setup: Retrieve ARM Mac LUCI packages

Retrieve LUCI packages for arm64 Macs in bootstrap.

Change-Id: I9ca9c57d3b64f7bb0107ec8f34f04a478636cd41
Bug: 458
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/61240
Pigweed-Auto-Submit: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Ted Pudlik <c7372cc3e451acc046049fca9e050bcb2a4a3d11@google.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed