Cap BW estimation sample by per-RAT static BW

Sometimes the byte count reported in TrafficStats is abnormally high.  This may result in a very high BW estimation value. The maximum value allowed by current codes is 2000Gbps which is too high. Although this happens quite rarely, it will skew the estimation value. To filter out these cases, invalidate BW estimation samples if the estimation value is above ratio * per-RAT static BW value. The ratio is currently set to 15.

Bug: 197667077
Test: atest FrameworksTelephonyTests:com.android.internal.telephony
Change-Id: I9fa315a2b92761ece329da0ecb51da63b9c86149
Merged-In: I9fa315a2b92761ece329da0ecb51da63b9c86149