Fix intermittent failure in SNDTest and cleanup some helpers

[labkey-tchad]

Rationale

When testing the SND permissions UI, the combo box selection for all categories takes a moment to propagate to the individual categories.

org.junit.ComparisonFailure: expected:<[SND Reader]> but was:<[None]>
  at org.junit.Assert.assertEquals(Assert.java:117)
  at org.junit.Assert.assertEquals(Assert.java:146)
  at org.labkey.test.tests.snd.SNDTest.categoryPermissionsUI(SNDTest.java:2188)

Also making some improvements to address some test synchronization issues that I was hitting locally but aren't causing problems on TeamCity at the moment.

Related Pull Requests

• N/A

Changes

• Fix intermittent failure in SNDTest.categoryPermissionsUI
• Cleanup some SND test components