Error message should use "ambiguous monomer" instead of "variant monomer"

[AlexeyGirin]

Steps to Reproduce

1. Toggle to Macro - Flex mode
2. Load IDT from paste from clipboard way: (Y:)
   

Actual behavior
System throws an error: Convert error! Given string could not be loaded as (query or plain) molecule or reaction, see the error messages: 'Invalid IDT variant monomer (Y:)'

Expected behavior
System throws an error: Convert error! Given string could not be loaded as (query or plain) molecule or reaction, see the error messages: 'Invalid IDT ambiguous monomer (Y:)'

Versions

• Ketcher Version 2.25.0-rc.1 Build at 2024-09-03; 15:31:03
• Indigo Toolkit Version 1.24.0-rc.1.0-gb8f099851-wasm32-wasm-clang-19.0.0
• Chrome Version 128.0.6613.114 (Official Build) (64-bit)
• Win10

Reference issues: #1619