tests: add missing trailing 'cd ..'
Many tests didn't change back from subdirectories at the end of the tests ...
and they don't have to. The missing 'cd ..' could always be added when another
test case is added to the test file.
This change do that tests (99.5%) consistently end up in $TESTDIR where they
started, thus making it simpler to extend them or move them around.
tests: cleanup of tests that got lost in their own nested directories
Some tests ended up in a directory several directories deeper than $TESTTMP,
usually because some 'cd ..' had been forgotten between different test cases.
Add 'cd ..' where they are missing so the tests get back where they started.