Test
Minor Description
While working on LUCENE-8391 I had test failures when maxMergeAtOnce is larger than segmentsPerTier. For instance when all segments are on the same tier, the maximum number of segments that is allowed in the index is segmentsPerTier but because the tiered policy wants to find maxMergeAtOnce segments to merge, no segments will get merged if there are less than maxMergeAtOnce segments.