first-login: tweak location formatting

[jbicha]

In the Welcome to Ubuntu wizard, my location is shown as America/New_York. This has a few issues.

1. I'd expect the _ to be removed so `America/New York'

2. Should we include the region or not?
   a. New York is a bit bad because I am in Florida and New York is over 1000 miles away from me (but we share the same time zone currently.) Shanghai is a similar problem for China.
   b. On the other hand, America/Edmonton isn't good either because America generally refers to the United States, while Americas or North America represent larger regions. I imagine including America would look like a typo or error to many people in Canada. I guess I can probably come up with more examples where the region is annoying than where it is helpful.

3. If the person doing the wizard is the same as the one who did the install, then New York might make sense but I imagine many people will also think it is a mistake since the page doesn't indicate that this is merely the timezone. Although it would be a major change, maybe it's better to just be more straightforward with wording like and the timezone you chose during installation.

Originally reported at LP: #1765233

[matthewpaulthomas]

If there is no file listing a human-sensible name for each time zone location, then let’s drop it and just say “the time zone you chose” instead.