scripted-diff: ci: Rework docker naming

DOCKER in names is confusingly used as synonym for "image", "container",
and "ci". Fix the confusion by picking the term that fits the context.

-BEGIN VERIFY SCRIPT-
 ren() { sed -i "s:$1:$2:g" $( git grep -l "$1" ) ; }

 ren DOCKER_PACKAGES CI_BASE_PACKAGES
 # This better reflects that they are the common base for all CI
 # containers.

 ren DOCKER_ID CI_CONTAINER_ID
 # This is according to the documentation of "--detach , -d: Run
 # container in background and print container ID".

 ren DOCKER_NAME_TAG CI_IMAGE_NAME_TAG
 # This avoids confusing with CONTAINER_NAME and clarifies that it is an
 # image.

 ren DOCKER_ADMIN CI_CONTAINER_CAP
 # This clarifies that it is a capability added to the container.

 ren DOCKER_CI_CMD_PREFIX CI_EXEC_CMD_PREFIX
 # This brings it in line with the CI_EXEC naming.

-END VERIFY SCRIPT-

ci/test/00_setup_env_mac.sh

@@ -7,7 +7,7 @@
 export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_macos_cross
-export DOCKER_NAME_TAG=ubuntu:20.04  # Check that Focal can cross-compile to macos
+export CI_IMAGE_NAME_TAG=ubuntu:20.04  # Check that Focal can cross-compile to macos
 export HOST=x86_64-apple-darwin
 export PACKAGES="cmake libz-dev libtinfo5 python3-setuptools xorriso"
 export XCODE_VERSION=12.2