fix: prevent lines removal on docstring insertion

[uinstinct]

Description

When generating docstring using the Continue menu > "Write a docstring for this code", it used to delete all lines after the first. This PR fix this behaviour.

• inside "continue.writeDocstringForCode" vscode command, for streamInlineEdit's onlyOneInsertion is now set to false

closes #4126

resolves CON-2048

Checklist

• [] I've read the contributing guide
• [] The relevant docs, if any, have been updated or created
• [] The relevant tests, if any, have been updated or created

Screenshots

[ For visual changes, include screenshots. Screen recordings are particularly helpful, and appreciated! ]

before.mp4

after.mp4

Tests

[ What tests were added or updated to ensure the changes work as expected? ]

Reproduction

This is flaky on the main branch - it works correctly on some code while not on other.
This code mostly gives removes the line after adding the lines so it can be used for testing.

def get_pc_model_class(name):
    global REGISTERED_PC_DATASET_CLASSES
    assert name in REGISTERED_PC_DATASET_CLASSES, f"available class: {REGISTERED_PC_DATASET_CLASSES}"
    return REGISTERED_PC_DATASET_CLASSES[name]

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Summary by cubic

Fixed an issue where inserting a docstring using the Continue menu would remove lines after the first, preserving the rest of the code.

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Name	Link
🔨 Latest commit	3323f18

[RomneyDa]

Need to review

[RomneyDa]

pausing merging while we compare with
#6159
which updates the onlyOneInsertion logic
onlyOneInsertion appears to only be used for docstring, so wondering why it was added in the first place