Remove unused menu items from Tor Browser help menu

A number of Help menu items in Tor Browser apply only to Firefox or are broken in Tor Browser. In particular:

"Tor Browser Help" is actually a help menu for Firefox
"Tor Browser Tour" is really a Firefox Tour
"Tor Browser Health Report" is a Firefox Health Report to Mozilla that doesn't work on Tor Browser
"Submit Feedback..." sends feedback to Mozilla
"Restart with Addons Disabled" is inadvisable

So I would suggest removing these menu items.

I have considered the possibility of renaming "Tor Browser Help" and "Tor Browser Tour" to "Firefox Help" and "Firefox Tour" and leaving them in, but I fear this may be confusing to users. More importantly, we should add a menu item with a true "Tor Browser Help"; see legacy/trac#11698 (moved).

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