SI-8835 Iterator tests can be junit

Without loss of generality or convenience, but helps
reduce the number of files in test/files and may reduce
compile times for test suite.

This commit includes the fix from #3963 and an extra
test of that fix that ensures the stack doesn't grow
on chained drops.
SI-8835 Update iterator tests

Addressing feedback from the collections test czar,
updated a few of the primitive tests.  Avoided testing
addition and just asserted.

Updated indexOf test to test Iterator.indexOf.
Merge pull request #4075 from som-snytt/issue/8835-junit

SI-8835 Iterator tests can be junit