RNA Builder: Default preset name changes unexpectedly after switching phosphate picker from 3' to 5'

[MarinaKisacik]

Found while testing #9120
Steps to Reproduce:

1. Switch to Macro mode
2. Expand the RNA builder in the RNA tab of the Monomer library
3. Select a sugar, a base, and a phosphate for the preset
4. Note the default preset name that appears in the name input field
5. Change the phosphate position from 3' to 5'
6. Observe the preset name field

Actual Results
The default preset name is changed

Expected Result:
The default preset name should remain unchanged, regardless of any changes to the phosphate position picker

Found in Environment:

• Ketcher Version 3.15.0-rc.1 Build at 2026-04-02; 15:41:30
• Indigo Version 1.43.0-rc.1.0-gd74653443-wasm32-wasm-clang-19.0.0
• Chrome Version 146.0.7680.178 (Official Build) (64-bit)
• Win11