When bad RxQual causes handover to a cell with weaker RxLev, then
handover oscillation *will* happen, as shown in test_rxqual.ho_vty.
Introduce a penalty timer for a cell where we had bad RxQual.
This delays handover back to the cell with stronger RxLev by the penalty
timeout; hopefully the interference is gone after the timeout.
Usually, we set new configuration elements so that osmo-bsc behaves the
same as before the config item was added. In this instance, this makes
no sense, because no-one ever wants handover oscillation from bad
RxQual, which is guaranteed to happen without the new penalty timer. Set
it to 60 seconds by default, same as other penalty timers.
Related: SYS#5911
Change-Id: I057b156604a104a26a7ce45d1c7adadbf452c932