BUG/MINOR: quic: remove max_bw filter from delivery rate sampling

BUG/MINOR: quic: remove max_bw filter from delivery rate sampling

This filter is no more needed after this commit:

 BUG/MINOR: quic: fix BBB max bandwidth oscillation issue.

Indeed, one added this filter at delivery rate sampling level to filter
the BBR max bandwidth estimations and was inspired from ngtcp2 code source when
trying to fix the oscillation issue. But this BBR max bandwidth oscillation issue
was fixed by the aforementioned commit.

Furthermore this code tends to always increment the BBR max bandwidth. From my point
of view, this is not a good idea at all.

Must be backported to 3.1.