BUG/MINOR: quic: fix discarding of already stored out-of-order ACK

BUG/MINOR: quic: fix discarding of already stored out-of-order ACK

To properly decount out-of-order acked data range, contiguous or
overlapping ranges are first merged before their insertion in a tree.

The first step ensure that a newly reported range is not completely
covered by the existing tree ranges. However, one of the condition was
incorrect. Fix this to ensure that the final range tree does not contain
duplicated entry.

The impact of this bug is unknown. However, it may have allowed the
insertion of overlapping ranges, which could in turn cause an error in
QUIC MUX txbuf window, with a possible transfer freeze.

No need to backport.