tests: use waitKeeperReady instead of WaitDBUP.
tests: use waitKeeperReady instead of WaitDBUP.

Like done in other tests use waitKeeperReady that will also check if the
clusterdata reports the keeper as initialized or WaitDBUP may catch the db up
when it's instead initializing (if starts and stop few times).

siepkes/stolon,sgotti/stolon,sgotti/stolon,sorintlab/stolon,siepkes/stolon,sorintlab/stolon