Sometimes when multiple cypress processes load the same support file
in parallel, a race condition is encountered as file copy operations
are performed. As a result, the content of the support file is not
loaded and cypress tests will fail (see https://jenkins.softwareheritage.org/blue/organizations/jenkins/DWAPPS%2Ftests-on-diff/detail/tests-on-diff/2084/pipeline/124).
So use a specific copy of the support file for each cypress runner
to mitigate that issue.