* Fix TimeSeriesLifecycleActionsIT.testShrinkAction
Shrinking a 6 shard index to 3 shards can be quite time consuming and
assertBusy probes the conditions at exponentially growing intervals.
This separates the one assertion that was used for all the conditions
into multiple assertBusy statements and increases the timeout for waiting
for the shrink to complete.
* Allow more time for shrink to complete
This commit allows more time for the shrink operation to complete in
testRetryFailedShrinkAction (separating the assertBusy calls too) and
testMoveToRolloverStep.
* Shrink to no more than 2 shards in tests
(cherry picked from commit 5fe780148fa3536915d61475b087896a5b9ace82)
Signed-off-by: Andrei Dan <andrei.dan@elastic.co>