kata-deploy: Remove temporary directory after creating tarball

The various tarballs are unpacked into a temporary directory, and then that
directory is compressed into kata-static.tar.xz. After we have the tarball,
there is no reason to keep the temporary directory. Dispose of it as the last
step.

Fixes: #6490
Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

tools/packaging/kata-deploy/local-build/kata-deploy-merge-builds.sh

@@ -25,4 +25,5 @@ done
 
 echo "create ${tar_path}"
 (cd "${tarball_content_dir}"; tar cvfJ "${tar_path}" .)
+rm -rf "${tarball_content_dir}"
 popd