Remove dialog titles from simple package installer dialogs.

- Checked the wording of the content of the dialogs and I think the
  title does not add any information. Design guidelines discourage
  dialog titles.
- Removed unused dialog type
- Removed now unused strings
- Spell corrected a string

Bug: 5526317
Change-Id: I7d125d92ef3a2fb3fd6fd402af8d2422c0d8b869