SPECIAL_MAJOR logic doesn't work correctly for releases prior to the breakpoint

[bhearsum]

We generate the list of major releases in two ways:

1. Everything before the breakpoint version is considered "old history", and kept unconditionally.
2. Everything after that is subject to a number of sanity checks

Unfortunately, these sanity checks do not work well with the SPECIAL_MAJOR lists we define elsewhere, leading to any versions in them being ignored as major versions if they are past the breakpoint.

We need to fix this, as 125.0.1 is considered a special major version.

[bhearsum]

Might be fixed by https://bugzilla.mozilla.org/show_bug.cgi?id=1891921 (cc @JohanLorenzo)