remove reslice logic

[kruskall]

Since the pooling was removed the protobuf slices are always empty

remove unnecessary reslice logic:

apm-data/input/elasticapm/internal/modeldecoder/modeldecoderutil/slice.go

Line 26 in 0ca8fce

func Reslice[Slice ~[]model, model any](slice Slice, n int) Slice {