Add startTest() to all TestFlows

[mdrichardson]

Fixes #3231

Description

Mostly no-op, but makes debugging a little easier. See linked issue for more info.

Note that for tests that rely on done() this won't do much until the tests are converted to using async/await. There's some tests where a then(done) exists in the chain and it didn't seem to matter whether startTest() was added before or after it. It will be irrelevant, anyway, when I convert them to async tests in #3226

Specific Changes

• Append startTest() to the end of all TestFlows

Testing

I edited a few flows to make them fail to confirm they all still work appropriately.

[coveralls]

Pull Request Test Coverage Report for Build 636623662

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 84.838%

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Totals
Change from base Build 636450762:	0.003%
Covered Lines:	18654
Relevant Lines:	20940

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💛 - Coveralls