Update BK platform/linux/builder queue to HEAD for updates rollup (#29)

* Update BK platform/linux/builder queue to HEAD for updates rollup

Bakery run: https://buildkite.com/improbable/platform-bakery/builds/654#8c35cb0c-73b8-42aa-9193-192562c61f5c

Platform PR: https://github.com/improbable/platform/pull/9005

Changes within packer/improbable.io/buildkite:
----------------------

* Update imp-tool-bootstrap version to the one that includes `subscribe --tools`. (improbable/platform#8932)
* Update imp-tool bootstrap version to 20190311.101729.57b4634585. (improbable/platform#8903)
* Update imp-tool-bootstrap version in platform.git docs. (improbable/platform#8854)
* Eng fix buildkite ansible (improbable/platform#8852)
* Add more quotes and fix the one-shot service installation (improbable/platform#8846)
* Tweaks to fix the local-ssd mount script in some cases. (improbable/platform#8843)
* Upgrade to golang 1.11.5 from 1.10.something (improbable/platform#8671)
* fixing staleness, works on macstadium (improbable/platform#8770)
* Update unreal agents to latest toolbelt version (improbable/platform#8738)
* ENG-1296: Adjust buildkite-agent process management to use --spawn (improbable/platform#8630)
* Make build-cloud able to deploy terraform without a human present. (improbable/platform#8729)
* Fix goss test. (improbable/platform#8730)
* Fix environment hook on Windows (improbable/platform#8720)
* Fix baking with a local SSD (improbable/platform#8680)
* Fix trigger-pipelines queue with if, not elif (improbable/platform#8677)
* ENG-1259: Fix missing var (improbable/platform#8674)
* ENG-1259: Add Linux support for local SSDs (improbable/platform#8534)
* BK drive-by: latest agent version (improbable/platform#8628)
* ENG-1275: Link to a new CI Health dashboard (improbable/platform#8605)
* ENG-1287: Add an isolated temp dir in the BuildKite agent environment hook (improbable/platform#8568)
* BK git: dammit. (improbable/platform#8626)
* BK driveby - new git. (improbable/platform#8624)
* Update imp-tool-bootstrap version. (improbable/platform#8588)
* set folder to staff (improbable/platform#8422)
* dont sleep and brew install vault (improbable/platform#8533)

Changes within go/src/improbable.io/cmd/imp-ci:
----------------------

* ENG-1281: imp-ci steps upload --from <paths/globs> (improbable/platform#8902)
* Expand ownership to EV team (improbable/platform#8905)
* FYS: improve logging in BK wrapper (improbable/platform#8885)
* ENG-1296: Reflect agent-count into the labels for scaler (improbable/platform#8741)
* COMP-549 Set up the sim node bake pipeline (improbable/platform#8433)
* ENG-1274: time BK step durations for later analysis (improbable/platform#8580)
* ENG-1275: Link to a new CI Health dashboard (improbable/platform#8605)

Changes within go/src/improbable.io/cmd/imp-vault:
----------------------

No changes in go/src/improbable.io/cmd/imp-vault

* Newest builder

See improbable/platform#9263.

Author: Peter Mounce

.buildkite/premerge.steps.yaml

@@ -11,10 +11,12 @@ common: &common
   agents:
     # Choose another capable_of_building once/if you have one.
     # If you parasite to platform's, you can be broken if the platform agents change.
-    # TODO(EV): Make docs better. (https://github.com/improbable/platform/blob/master/docs/product-groups/dev-workflow/buildkite/how-to-deploy-change-to-agents.md)
+    # See https://code.i8e.io/github.com/improbable/platform/-/blob/docs/product-groups/dev-workflow/buildkite/how-to-add-a-new-build-capability.md
     - "capable_of_building=platform"
     - "environment=production"
-    - "queue=v2-1545678177-378924f50bfed5a0-------z"
+    - "permission_set=builder"
+    - "platform=linux"
+    - "queue=${CI_BUILDER_QUEUE:-v2-1553093147-c5086c3db10e3761-------z}"
   timeout_in_minutes: 60 # TODO(ENG-548): reduce timeout once agent-cold-start is optimised.
   retry:
     automatic: