Help: Update presets release notes for 4.3

See commit 23615b7ca4 (presets: Allow jobs to match `ctest -j` with no
value, 2025-12-15) and commit 71ff5a9d6f (presets: Disallow negative
values for "jobs" fields, 2026-01-13) for the changes.

Also update `cmake-presets(7)` itself to correct the behavior change
from the prior commit not respecting the presets file version.