UWT table on Units view doesn't allow you to scroll down

[jwrober]

Describe the bug
If you have units waiting for UWT to expire and the list is bigger than the page, then you get a vertical scroll bar. If you try to scroll down, you can't. The game always drops you back to the top.

To Reproduce
Steps to reproduce the behavior:

1. Open a game with lots of units with UWT
2. Click on Units View
3. Try to scroll down to see the bottom one
4. See error

Expected behavior
Scroll bars work as expected.

Screenshots
If applicable, add screenshots to help explain your problem.

Platform and version (please complete the following information):

• OS: Linux
• Freeciv21 version: 3.1-beta.1
• Ruleset/Longturn game (if applicable):

Additional context
Came up as part of a conversation with @hugomflavio

[jwrober]

Offending code starts here

freeciv21/client/views/view_units.cpp

Line 285 in 5612c6d

QTimer *timer = new QTimer(this);

The QTimer updates every second and then repaints/updates the table. The purpose is to update the countdown timer in the table, but seems to have a deleterious effect with long lists.