Updates config migration to occur for any v0.30.x release rather than
specifically 30.4
Also updates the config for the rolling upgrade test to use 64 kib
segments, and use smaller files for the final upload of rolling upgrade.
Change-Id: I941f77fe2b9011b45f28a5f3a2430e882d2ae6b3
stage
The test-versions script no longer uses the `testfiles` directory, which
the final upload for the rolling-upgrade script depended on. This change
creates and populates a `testfiles` diirectory during the final upload
stage of the rolling upgrade test.
Change-Id: Iabeccbadc55a8c85a1febbd5eb4e7d889a57a8dc
