bsdinstall time: Revert dialogs titles

[asiciliano]

Summary

@jrtc27 , this review should fix:

Revert dialogs titles like before https://cgit.freebsd.org/src/commit/usr.sbin/bsdinstall/scripts/time?id=0e5c72c3cc5471dfa8cb42b018d623b1ef15dbe8: precisely delete spaces around titles to uniform to other installer components.

Test Plan

bsddialog --title 'Time & Date' --datebox '' 0 0

┌─────┤Time & Date├─────┐
│┌────┐ ┌─────────┐ ┌──┐│  
││2022│/│    March│/│23││  
│└────┘ └─────────┘ └──┘│  
├───────────────────────┤  
│  [  OK  ]   [Cancel]  │  
└───────────────────────┘

bsddialog --title 'Time & Date' --timebox '' 0 0

┌───┤Time & Date├───┐
│  ┌──┐ ┌──┐ ┌──┐   │  
│  │20│:│23│:│28│   │  
│  └──┘ └──┘ └──┘   │  
├───────────────────┤  
│[  OK  ]   [Cancel]│  
└───────────────────┘