Run GraphQL CI step outside of docker

Running each GraphQL sub-command in a separate docker container means
we don't need to have git installed in the app docker image.

.buildkite/pipeline.graphql.yml

@@ -1,13 +1,3 @@
 steps:
   - label: Update GraphQL docs
     command: .buildkite/update_graphql_docs
-    plugins:
-      - docker-compose#v4.9.0:
-          run: app
-          mount-ssh-agent: true
-          mount-buildkite-agent: true
-          env:
-            - API_ACCESS_TOKEN
-            - GIT_NAME
-            - GIT_EMAIL
-            - GH_TOKEN

.buildkite/update_graphql_docs

@@ -4,7 +4,11 @@ set -euo pipefail
 . bin/utils.sh
 
 echo "+++ Fetch latest schema (via GraphQL introspection)"
-rake graphql:fetch_schema >| data/graphql/schema.graphql
+docker compose run \
+  --no-deps \
+  -e API_ACCESS_TOKEN \
+  app \
+  rake graphql:fetch_schema >| data/graphql/schema.graphql
 
 echo "+++ Check for schema changes"
 if git diff --exit-code --quiet data/graphql/schema.graphql; then
@@ -21,12 +25,12 @@ BRANCH=buildkite-docs-bot/graphql/$(git rev-parse --short :data/graphql/schema.g
 PULL_REQUEST_NUMBER=$(get_branch_pull_request_number $BRANCH)
 
 if [ -n "$PULL_REQUEST_NUMBER" ]; then
-  buildkite-agent annotate  "Nothing to change, pull request [#$PULL_REQUEST_NUMBER](https://github.com/buildkite/docs/pull/$PULL_REQUEST_NUMBER) awaiting approval." --style "info"
+  buildkite-agent annotate "Nothing to change, pull request [#$PULL_REQUEST_NUMBER](https://github.com/buildkite/docs/pull/$PULL_REQUEST_NUMBER) awaiting approval." --style "info"
   exit 0
 fi
 
 echo "+++ Generate GraphQL docs"
-rake graphql:generate
+docker compose run --no-deps app rake graphql:generate
 
 echo "--- Commit and push changes"
 git add .