removeBond
Removes any existing bond for address. Returns true if a bond was present and removal was initiated.
Needed before connecting to a nRF Legacy-DFU bootloader that re-advertises at the same address as the app (e.g. AdaDFU): a leftover bond makes the OS force stale link encryption the fresh bootloader can't satisfy, so it drops the link on the first DFU command. Default no-op for platforms/impls that don't manage bonds.