floss: Delay CreateBond until discovery is done

We used to cancel discovery before CreateBond because BR/EDR connection
doesn't work when Inquiry is in progress. However, it is not enough if
LibBluetooth is dealing with Remote Name Request. To completely avoid
the conflicts between CreateBond and Inquiry/Remote Name Request, we
should wait until the discovery state changed.

Bug: 329857537
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: manual CreateBond when LibBluetooth is sending RNR, the request
      is delayed and success
Flag: EXEMPT, Floss-only changes
Change-Id: I72fcd9a9c47ac6e614b228e0c669676a85ac188b