Update language item from `share` to `sync`

[mdinger]

PR #16285 missed changing the language item from no_share_bound to no_sync_bound. PR #16780 made the manual consistent with the current language items. Everything must now be updated to sync.

The language item and the manual. The current language item:

// Variant name, Name, Method name;
...
NoSyncItem, "no_share_bound", no_share_bound;

[brson]

Good first bug.

[gamazeps]

I have very few experience on rust but I'll try if your ok with this ;)

[mdinger]

FYI, I tried to fix it at #16780 (comment) but started getting warnings. I couldn't find anything else to change with grep (I figured it should just be a name swap). 30-45 min compile times made this annoying when I didn't know what was wrong...

[mdinger]

Should be fixed.