Close the modified-on-disk dialog on a delayed onDisk-unmodified

This is a fix for a file deleted-created scenario where the created
signal is received later.

This change depends on the related change
903c62c192d2fd00d46ff15366990fb22aebbbb4 in ktextedit. Without that
change we might get a closed dialog even if the file has changed.

REVIEW: 122282