Costanalyzer bugfix: when a collection uuid is supplied, write the csv

Costanalyzer bugfix: when a collection uuid is supplied, write the csv
files with the name of the associated container request uuid, not the
collection uuid. Also change tests to use a proper temporary directory
for the outputs, and do not reuse that directory between tests (which
hid the bug this commit fixed).

refs #17187

Arvados-DCO-1.1-Signed-off-by: Ward Vandewege <ward@curii.com>