In the Flex mode, after pasting, the green selection of the fragment, that was copied, does not disappear

[ViktoriaTkacheva]

Steps to Reproduce

1. Switch to the Macro mode
2. Open this file Nucleotides and nucleosides.zip
3. Copy the top sequence and paste it at the very bottom below the other sequences
4. Verify the top sequence again

Actual behavior
The green selection of the top sequence does not disappear

Expected behavior
The green selection of the top sequence disappears

Screenshots

2024-05-17_15h21_00.mp4

Desktop (please complete the following information):

• OS: Windows 10 Pro (version 22H2) x64
• Browser: Сhrome
• Version: (124.0.6367.201) x64

Ketcher version 2.21.0-rc.2, Build at 2024-05-17; 12:09:53

Additional context
This bug can potentially lead to user input loss, if the user immediately starts editing the inserted fragment, deleting something in it. If this happens, the top fragment will also be deleted (as it remains selected), but the user will not see it, because the top fragment is out of the viewport

Issue found while testing #3916