On startup `gcTimeSum` might work fast and return `0`, so on this case
the algorithm turns in infinity loop which simple consume CPU on timer
which fires without any interval.
Use `5ms` as fallback to have interval `245ms` for that case.
Closes: https://github.com/containerd/containerd/issues/5089
Signed-off-by: Kirill A. Korinsky <kirill@korins.ky>
