Option "Send to active instrument track" preserves existing FX-plugins

This may be intended?
OS : winXP sp3
LMMS 1.1.90-g33d8c44

**Issue description:**
If the sidebar option *"Send to active instrument track"* is used, the existing preset (the active) will not be completely overwritten. The existing plugins in FX-Tab is preserved in the 'new' preset, and it is kind of a 'hybrid' between the existing and the inserted

**Scope**
zasfx, AFP, & Kicker will preserve inserted FX, all the others overwrites the FX content.

**Recreate :**
Open an empty project
Insert an zasfx empty instrument
Add any effect on the FX-tab. (i just took dual filter)
Keep FX-tab open
Open the zasfx presets
Right-click on Pads | sine-pad0001
Use option "Send to active instrument track"
The preset sine-pad0001 is inserted in the opend/active preset, but the filter in the FX-tab is preserved.
I also tried with 3oc. Those presets are completely replaced, and an 3oc preset, will also completely replace a zasfx preset. That is not the case for zasfx

(That was how i messed up in 3415.

Start by reproducing the sidebar option "Send to active instrument track" with an zasfx instrument, an existing FX-tab effect, and the sine-pad0001 preset. Compare the replacement behavior across zasfx, AFP, Kicker, and 3oc; done means the intended FX preservation behavior is consistent and covered by a regression test.

Written by the indexing model from the issue text.