Revert "bonding: replace bond member raw ifcfg files rather than append"

This reverts commit b1c4598e476bdc649ea0aaec4e40a3131b46d34d.

Removed as a result of upstream changes to the bridging setup, see commit
2db6d7111870c5d16d812d9cddc23558f3f4a202 for details.