Remove --force-build command in cache steps in CI

The `--force-build` command has not been used for a long time
in the `ci-image build` command for quite some time because the
sheer fact that you run the command means that you want to run
the build (so it made no sense to have it). The command only makes
sense when you want to force build when running `breeze` or
`breeze start-airflow` command.

However commands to build cache in CI still had this command used
and it caused the builds to fail after merging apache#35768 when the
option has been removed (it was not detected there, because
cache steps only run in main build)

.github/workflows/ci.yml

@@ -232,7 +232,6 @@ jobs:
           --builder airflow_cache
           --prepare-buildx-cache
           --run-in-parallel
-          --force-build
           --platform ${{ matrix.platform }}
         env:
           DEBUG_RESOURCES: ${{needs.build-info.outputs.debug-resources}}
@@ -1890,7 +1889,6 @@ jobs:
           --builder airflow_cache
           --prepare-buildx-cache
           --run-in-parallel
-          --force-build
           --platform ${{ matrix.platform }}
         env:
           DEBUG_RESOURCES: ${{needs.build-info.outputs.debug-resources}}