Add/Remove hydrogens cleans up valence value if its equal 8

**Steps to Reproduce**
1. Put on the canvas following SMARTS: `[#6]#[F;v8]#[#6]`
2. Press Add/Remove implicit hydrogens button

**Actual behavior**
System folds 2 hydrogens (this is correct), cleans up valence value and shows valence problem sign (red underline)

**Expected behavior**
System folds 2 hydrogens (for central atom)

**Ketcher version** [e.g. v2.4.2].
- Indigo Toolkit Version 1.18.0.0-g73c32dec3-wasm32-wasm-clang-12.0.0
- Ketcher Version 2.19.0-rc.2 Build at 2024-03-11; 12:30:30
- Chrome Version Version 122.0.6261.112 (Official Build) (64-bit)
- Win10
- Issue found while testing https://github.com/epam/Indigo/issues/1436

Start by reproducing the SMARTS case `[#6]#[F;v8]#[#6]` in the Add/Remove implicit hydrogens flow using the reported Indigo WASM and Ketcher versions. Trace how the central atom's valence is handled after two hydrogens are folded. Done means the hydrogens are added while the valence value remains valid and no valence-problem marker appears.

Written by the indexing model from the issue text.