More cleanup/typos in TCK

[scottkurz]

1. StartLimitTests

• Fix comment: Tests that allow-start-if-complete "trumps" start-limit in the sense

2. DoSomethingArrayItemReaderImpl has a confused checkpoint strategy in the boundary case of ‘zero’… with an item-count of 1. It works though
3. timestamps mixed in metricstests (from junit and from jobexecution) - inconsistent print formatting
4. unused 2nd step: should be called out in some form: ExecutionTests#testInvokeJobWithNextElement
5. For ParallelExecTests# testPartitionedMapperOverrideFalseOnRestart, we’re using a different # of partitions on restart with override = false. So in expecting the job to complete with a successful exit status, we’re requiring an impl doesn’t flat out mark this invalid and fail to allow restart altogether.

• Test comment is weak
• Let’s also check for completed batch status since that’s another part of what we’re trying to test).