Show selectors scrollbar in all pages

[wu-sheng]

The current selector(service group/service/instance/endpoint) in all pages supports scrolling, but it is not clear.

@Fine0830 Please help on polishing this a little.

[Fine0830]

We should set scroller in computer system settings.

[wu-sheng]

I have set that too on the MacOS, but nothing shows on the Chrome.

[Fine0830]

Close this via apache/skywalking-rocketbot-ui#426

[wu-sheng]

Please sync the submodule when you have time.