Hide version text in About dialog when version is unavailable in unauthenticated state

[chlins]

Steps to Reproduce

1. Open Harbor portal in a browser
2. Do not log in
3. Click the "About" link in the top navigation bar
4. Observe the About dialog

Expected Behavior

When version is not available (i.e., user is not logged in), the version line should be hidden entirely.

Actual Behavior

The version line is always shown, resulting in a bare Version: label with no version number when the user is not logged in.