S-group label shown at the bottom right corner of S-group brackets - not clear what bond/atom it is addressed to

**Steps to Reproduce**
1. Load from file: [aaaaaaaaaaaaaa.zip](https://github.com/epam/Indigo/files/14906267/aaaaaaaaaaaaaa.zip)

**Actual behavior**
User ( @MChislov ) says that if he look on the molecule - not clear what bond/atom "Z" labels is addressed to

**Expected behavior**
He would prefer to have that label at the center of S-group in the same manner as it is done in Marvin

As per @AlexanderSavelyev **decision** - we have to put label in the center by default ONLY if s-group contains one atom or bond only!

**Versions:**
Windows 10
Chrome Version 112.0.5615.138 (Official Build) (64-bit)
Ketcher Version 2.20.0-rc.2 Build at 2024-04-02; 05:31:05
Indigo Toolkit Version 1.20.0-dev.1.19-gd0224f91-wasm32-wasm-clang-12.0.0

Start by loading aaaaaaaaaaaaaa.zip in the molecule editor and reproducing the S-group label placement shown in the report. Trace the S-group rendering entry point and verify the decision: center the label by default only when the S-group contains one atom or one bond, while preserving the expected placement for larger groups.

Written by the indexing model from the issue text.