Secondary default tab cannot be built

Secondary tab cannot be built consistently due to deeper default tab parent items clearing the primary default tab.

Basically, in #1119782: Default Tasks need "No menu entry" option for parent menu item the logic for "No menu entry" is added to create a default tab. The argument was made for building a menu item regardless of the setting because Page Manager should take charge for all paths it defines. However, when building a secondary menu item, if the dummy secondary tab (only way to achieve secondary tabs as far as I can see) page comes after the primary, the primary tab will disappear as MENU_CALLBACK (as overridden by the secondary tab page menu settings).

P.S. Strongly suspect this also causes #2274881: Default primary menu tab disappears after menu rebuilding.