This updates upgrade tests to run two flows with 3+1 clusters:
1. 0.3 -> current (testing upgrade with partition wiping)
2. 0.4-alpha.7 -> current (testing upgrade without partition wiping,
boot-a/boot-b)
And small upgrade with preserve enabled for single-node cluster.
Provision tests are now split into two parallel tracks in Drone.
Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>
