Fix dashboard greetings that show 'good morning' after noon

Updated dashboard greetings to show "Good afternoon" after 12:00 instead of 13:00.

Updated time periods for greetings:
- Morning: 5:00 to 11.59
- Afternoon: 12:00 to 17.59
- Evening: 18:00 to 21:59
- Night: 22:00 to 4.59

Updated night-time greeting to "Hello" as "Good night" is a kind of goodbye.

Closes #24938.

Signed-off-by: Nina Pypchenko <22447785+nina-py@users.noreply.github.com>