Glissando portamento playback on 3.5-dev issues

Download compiled MuseScore with portamento support for fluid: https://github.com/musescore/MuseScore/pull/5853/checks?check_run_id=52…
PR: https://github.com/musescore/MuseScore/pull/5853/files

How to reproduce the first issue:
- Put some notes on the score, more than 4, leaving two different notes together in the middle, so that you can connect them with a glissando.
- Tie these 2 notes in the middle with a glissando and set it to portamento. Suppose the tied notes are C and F.
- Put playback from the beginning of the score. It works correctly. You hear the glissando from C to F.
- Start the playback from the first tied note (C). It still sounds correctly, with portamento from C to F.
- Start the playback from a random note anywhere after the glissando notes. You will hear a portamento from C to that note, what shouldn't happen, since there is no glissando there.

How to reproduce the second issue:
- Put two identical notes on the score side by side and tie them with +, so they work as a single note.
- Right after them, put a 3rd note with a different pitch.
- Connect the 2nd note with the 3rd with a glissando and set it to portamento.
- You expect to hear a note with starts with a fixed pitch and (1st note) and, when the 2nd note is reached, the portamento playback starts.
- What you get: no portamento playback.