apacheGH-43743: [CI][Docs] Ensure creating build directory

It's used as a volume. If it doesn't exist, `docker compose` reports
an error:

    Error response from daemon: invalid mount config for type "bind": bind source path does not exist: /home/runner/work/crossbow/crossbow/build/

dev/tasks/docs/github.linux.yml

@@ -34,8 +34,10 @@ jobs:
         env:
           ARROW_JAVA_SKIP_GIT_PLUGIN: true
         run: |
+          mkdir -p build
           archery docker run \
             -e SETUPTOOLS_SCM_PRETEND_VERSION="{{ arrow.no_rc_version }}" \
+            -v $PWD/build/:/build/ \
             {{ flags|default("") }} \
             {{ image }} \
             {{ command|default("") }}
@@ -45,7 +47,7 @@ jobs:
           ref: {{ default_branch|default("main") }}
           path: crossbow
           fetch-depth: 1
-      {% if  publish %}
+      {% if publish %}
       - name: Prepare Docs Preview
         run: |
           # build files are created by the docker user

dev/tasks/tasks.yml

@@ -1486,15 +1486,14 @@ tasks:
       image: debian-go
   {% endfor %}
 
-  # be sure to update binary-task.rb when upgrading ubuntu
+  # be sure to update binary-task.rb when upgrading Debian
   test-debian-12-docs:
     ci: github
     template: docs/github.linux.yml
     params:
       env:
         JDK: 17
       pr_number: Unset
-      flags: "-v $PWD/build/:/build/"
       image: debian-docs
       publish: false
     artifacts:
@@ -1620,6 +1619,5 @@ tasks:
       env:
         JDK: 17
       pr_number: Unset
-      flags: "-v $PWD/build/:/build/"
       image: debian-docs
       publish: true