Move the test name computation out of _generate_test

The test name is now computed in _finalize_params. This gives better
separation of concerns: it was not _generate_test's job to configure
the test parameters. More will be moved to _finalize_params in
follow-up CLs.

Bug: 330885075
Change-Id: I525b60231c113b5eaaeaf899f6412e63749e159d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5378645


Reviewed-by: Andres Ricardo Perez <andresrperez@chromium.org>
Commit-Queue: Jean-Philippe Gravel <jpgravel@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282118}