Previously we were rebuilding the record when we performed a filtering
operation. This caused a lot of copying of data. Instead we now just
mark the filtered our values as null in the array bitmap.

name           old time/op    new time/op    delta
FilterData-10    5.00ms ± 2%    0.38ms ± 1%  -92.37%  (p=0.000 n=10+10)

name           old alloc/op   new alloc/op   delta
FilterData-10    6.28MB ± 0%    0.00MB ± 1%  -99.94%  (p=0.000 n=10+10)

name           old allocs/op  new allocs/op  delta
FilterData-10     3.91k ± 1%     0.07k ± 2%  -98.19%  (p=0.000 n=10+10)

This prevents us from having to skip over records later and other
footguns where we Sum which accesses the data directly and ignores nulls