docs(visualization): drop self-inflicted fixes from unreleased changelog (#4499)

The Fixed section listed many regressions introduced and resolved within
this same unreleased UI-rewrite cycle (DaisyUI migration, Angular Material
removal, new metrics bar/sidebars/popovers). Those never reached a released
version, so they fix nothing a 1.142.0 user experienced. Keep only the
entries that address bugs present in 1.142.0 or earlier.

Co-authored-by: Christian Hühn <christian.huehn@maibornwolff.de>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>