Merge pull request #185 from johnpaulalex/test_doc6

test_sys_checkout: Inline most config generation functions.


(because most of them only had one caller).

Besides the one-offs, many tests were reusing the _write_tag_branch_hash() config – except test_container_exclude_component (which now uses it) and test_container_component (which now makes its own custom config inline).

At this point the tests are starting to be self-explanatory and self-contained: create a config with particular sections, check out that config, then make sure the resulting status (and file existence) are as expected.

User interface changes?: No

Fixes: N/A

Testing:
test removed: None
unit tests: None
system tests: 'make stest' passes
manual testing: None