There was an issue around the time of Qt 4.6 when placeholder text was
introduced, that caused a compile failure when it was specified in the
form.
As a workaround the placeholder texts were moved to the code.
Qt 4 hasn't been relevant to us for ages. So move all (non-parametrized)
placeholder texts to the form files instead.
It's better to keep this kind of text content together. Makes sure
translate/no-translate status is kept as it is.
- also fixes indentation in one file (auto fixed by Qt Designer)
- removes several default parameters, which are not needed in the files
- related to #4840 (but not intended as fix for a no-bug)
