Slight caching improvement in image building (#45283)

Packaging tools (uv and pip) do not have to use mounted cache as
they are always reinstalled when their versions got updated in the
Dockerfile, and changing sources of airflow does not invalidate the
installation step (COPY . is made after the installation).

This will add two more layers being cached in github registry when
the image is built.

Follow-up after #45266

Dockerfile.ci

@@ -1285,8 +1285,7 @@ ARG DEPENDENCY_CACHE_EPOCH="0"
 # Install useful command line tools in their own virtualenv so that they do not clash with
 # dependencies installed in Airflow also reinstall PIP and UV to make sure they are installed
 # in the version specified above
-RUN --mount=type=cache,id=ci-$TARGETARCH-$DEPENDENCY_CACHE_EPOCH,target=/root/.cache/ \
-    bash /scripts/docker/install_packaging_tools.sh
+RUN bash /scripts/docker/install_packaging_tools.sh
 
 COPY --from=scripts install_airflow.sh /scripts/docker/