doc: Remove old changelog fragments

doc/changes/auxiliary/mr.444.1.md

doc/changes/auxiliary/mr.444.2.md

doc/changes/auxiliary/mr.469.md

doc/changes/auxiliary/mr.493.1.md

doc/changes/auxiliary/mr.493.md

doc/changes/auxiliary/mr.574.1.md

doc/changes/auxiliary/mr.574.2.md

doc/changes/compositor/mr.425.md

doc/changes/compositor/mr.433.md

doc/changes/compositor/mr.436.md

doc/changes/compositor/mr.477.1.md

doc/changes/compositor/mr.477.2.md

doc/changes/compositor/mr.479.md

doc/changes/compositor/mr.481.md

doc/changes/compositor/mr.495.md

doc/changes/compositor/mr.501.md

doc/changes/compositor/mr.502.md

doc/changes/compositor/mr.538.md

doc/changes/compositor/mr.547.md

doc/changes/compositor/mr.566.md