Fix rails package versions for dev builds.

Fix rails package versions for dev builds.

[ $goversion > $railsversion ] doesn't compare versions, it just
creates an empty file called $railsversion and returns success.  As a
result, the arvados-api-server and arvados-workbench package
numbers (and the rebuild-or-reuse decisions) were based only on the
last change to cmd/arvados-server, disregarding more recent changes in
the respective Rails projects.

refs #15819
refs #15863

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tclegg@veritasgenetics.com>