Micro: Merging aromatic compaund with functional group OR salt/solvent from Structure library make it disappear

Issue found in the context of testing #3630

UPDATE: It works the same not only with functional groups/salts/solvents but atom from Extended table or Periodic table

**Steps to Reproduce**
1. Start from empty canvas (Molecules view)
2. Add on the canvas: any functional group (Ac in my case), salt (acetic acid in my case) and two benzene rings
3. Merge each benzene ring with Ac and acetic acid

**Actual behavior**
Functional group and salt - DISAPPEARS

https://github.com/epam/ketcher/assets/26869421/e7a1510b-f99e-4397-8aea-28ef332d0db4

**Expected behavior**
System removes abbreviation and merges compounds

**Desktop (please complete the following information):**
- OS: win10
- Browser Chrome 120.0.6099.110 (Официальная сборка), (64 бит)

**Ketcher version** [e.g. v2.4.2].

No source file or test is named. Reproduce the steps in the Molecules view with benzene rings and functional-group, salt, solvent, or table atoms, then trace the merge handling for these structure-library items. Done means the abbreviation is removed while the compounds remain merged instead of disappearing.

Written by the indexing model from the issue text.