Build CI with bus encryption (#74)

I can't see a prod config to update so this PR only updates the CI cloudbuild config

Dockerfile

@@ -6,6 +6,7 @@ ARG LOG_PUBLIC_KEY
 ARG OS_PUBLIC_KEY1
 ARG OS_PUBLIC_KEY2
 ARG GIT_SEMVER_TAG
+ARG BEE
 ARG CONSOLE
 
 # Install dependencies.
@@ -35,6 +36,7 @@ ENV LOG_ORIGIN=${LOG_ORIGIN} \
     OS_PUBLIC_KEY1="/tmp/os1.pub" \
     OS_PUBLIC_KEY2="/tmp/os2.pub" \
     GIT_SEMVER_TAG=${GIT_SEMVER_TAG} \
+    BEE=${BEE} \
     CONSOLE=${CONSOLE}
 
 RUN make imx

release/cloudbuild_ci.yaml

@@ -21,6 +21,7 @@ steps:
           --build-arg=OS_PUBLIC_KEY1=${_OS_PUBLIC_KEY1} \
           --build-arg=OS_PUBLIC_KEY2=${_OS_PUBLIC_KEY2} \
           --build-arg=GIT_SEMVER_TAG=$(cat /workspace/fake_tag) \
+          --build-arg=BEE=${_BEE} \
           --build-arg=CONSOLE=${_CONSOLE} \
           -t builder-image \
           .
@@ -146,6 +147,7 @@ substitutions:
   # Build-related.
   _FIRMWARE_BUCKET: armored-witness-firmware-ci-1
   _TAMAGO_VERSION: '1.21.5'
+  _BEE: '1'
   _CONSOLE: 'on'
   # Log-related.
   _ENTRIES_DIR: firmware-log-sequence
@@ -156,4 +158,4 @@ substitutions:
   _LOG_PUBLIC_KEY: transparency.dev-aw-ftlog-ci+f5479c1e+AR6gW0mycDtL17iM2uvQUThJsoiuSRirstEj9a5AdCCu
   _OS_PUBLIC_KEY1: transparency.dev-aw-os1-ci+7a0eaef3+AcsqvmrcKIbs21H2Bm2fWb6oFWn/9MmLGNc6NLJty2eQ
   _OS_PUBLIC_KEY2: transparency.dev-aw-os2-ci+af8e4114+AbBJk5MgxRB+68KhGojhUdSt1ts5GAdRIT1Eq9zEkgQh
-  _CHECKPOINT_CACHE: 'public, max-age=30'
+  _CHECKPOINT_CACHE: 'public, max-age=30'