fix #24711: wrong chord height on 1.3 import

Scores that used the old default chord height (-4sp) were being loaded
using the new default chord height (0sp) and hence had chords much too
low.
fix tests, added new test

the new test is just a basic chord symbol compatibility test, which we
needed anyhow
Merge pull request #703 from MarcSabatella/24711-chord-height-read114

fix #24711: wrong chord height on 1.3 import