Fix e2e tests on Mac

[vitvakatu]

Pull Request Description

Some e2e tests (about leaving nodes) were always failing on my machine because of the race condition in the tests. The issue was caused by edges positions lagging behind for a few frames when switching Enso functions, which caused incorrect handling of clicks in the test code.

Now we wait for edges being initialized and node sizes being updated.

Thanks to @farmaazon for helping with debugging.

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.