Fix tab management and random data generation

[labkey-tchad]

Rationale

1. doAndWaitForWindow was implemented incorrectly. It needs to switch to the named window before calling doAndMaybeWaitForPageToLoad so that the page load is correctly detected.
2. When updating TestDataGenerator.getDefaultDataSupplier to generate random data for textChoice fields, I assumed that we weren't generating random data for other field types with a conceptURI. We are generating random values for some Sample columns so I've restored the old behavior for other column types.

Related Pull Requests

• Add support for generating random text choice data #2616
• Wait for system maintenance page to load when rerunning the task #2615

Changes

• Switch to target window before waiting for page load
• Fix random data generation for sample fields

[labkey-tchad]

Verify fix on TC: https://teamcity.labkey.org/buildConfiguration/LabKey_257Release_Premium_CommunitySqlserver_DailyASqlserver/3625493