Set explicit height on infinite scroll target

[gabalafou]

Fixes #312.

Description

While I was reviewing #356, I think I discovered why the infinite scroll React component wasn't doing its job. For whatever reason, it requires that the scrollable target has its height explicitly set—so height 100% rather than height auto.

Pull request checklist

• [x] Did you test this change locally?
  • Yes, but I only tested this with environments in a single namespace
• [x] Did you update the documentation (if required)?
  • No docs to update
• [ ] Did you add/update relevant tests for this change (if required)?
  • I need to see if there's a way to add an automated regression test for this

[gabalafou]

@PhilipNeffOnGithub could you try testing this locally?

[peytondmurray]

Thanks for this! :rocket: