lupdate doesn't update an existing .ts file with new comments for translators

<Issue>
When there's an already existing .ts file without comments for translators(https://doc.qt.io/qt-6/i18n-source-translation.html#add-comments-for-translators), running lupdate again for the same .qml file with newly added comments for translators doesn't update the .ts file.

<Reproduction Step>

1. Clone https://git.qt.io/mikio_hirai/multi-language-blog/-/tree/master?ref_type=heads
2. Check the original qml_ja_JP.ts file without comments for translators.
3. Update the Main.qml with the attached Main.qml to this ticket, which contains comments for translators.
4. Run the lupdate as follows

C:\work\i18n_test\multi_language>C:\Qt\6.7.1\msvc2019_64\bin\lupdate.exe . -extensions qml -ts i18n/qml_ja_JP.ts 

1. Check the qml_ja_JP.ts

<Expected result>
qml_ja_JP.ts has newly added comments for translators

<Actual result>
qml_ja_JP.ts doesn't have newly added comments for translators

<Workaround>

Generate another .ts file, instead of updating the existing one. (The one generated on my side is atteched to this ticket)

C:\work\i18n_test\multi_language>C:\Qt\6.7.1\msvc2019_64\bin\lupdate.exe . -extensions qml -ts i18n/qml_updated_ja_JP.ts