Utils: make column of convertPosition 0-based to merge it into Position

Change-Id: I239b3cb33b8ad59ac4097c919155ab5ca7d57b8e
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/languageclient/languageclientcompletionassist.cpp

@@ -447,7 +447,6 @@ IAssistProposal *LanguageClientCompletionAssistProcessor::perform()
     if (!Utils::Text::convertPosition(interface()->textDocument(), m_pos, &line, &column))
         return nullptr;
     --line; // line is 0 based in the protocol
-    --column; // column is 0 based in the protocol
     params.setPosition({line, column});
     params.setContext(context);
     params.setTextDocument(