RSRP-240789: Code Completion of Parameter Names in Strings Leaves Garbage Behind

One of the repro scenarios:

    public void Do(string stringValue, int intValue)
    {throw new ArgumentOutOfRangeException("");}

Place caret inside "". A parameter name is expected, so completion should be suggesting the param names.

Invoke basic completion with Ctrl+Space. Type "sv". Choose stringValue from the list, if not yet, and accept with Enter. You get:

    public void Do(string stringValue, int intValue)
    {throw new ArgumentOutOfRangeException("stringValuesv");}

Note the undesired sv suffix which was a completion prefix but failed to be replaced with the completed content.