Bug 24221: Move OPACMySummaryNote to HTML customizations in additional-contents

Bug 24221: Move OPACMySummaryNote to HTML customizations in additional-contents

To test:
1- Before applying the patch add some content to the system preference OPACMySummaryNote
2- Apply patch
3- restart_all and updatedatabase
4. Go to additional-content.pl ( HTML customizations )
5. You should now see your content from the system preference under OpacMySummaryNote in HTML customizations
6. Try searching for the system preference, OPACMySummaryNote. It has been removed and you should not be able to find it.
7. Try changing/removing/adding content from OpacMySummaryNote in HTML customizations
8. Make sure your edits are reflected when you look at the user summary page

Note: The system preference was named OPACMySummaryNote but in to be more consitent with how we have named other additional_contents I have renamed this OpacMySummaryNote.
Signed-off-by: shiyao <shiyao@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>