Tweak generation frequencies in ChainDB q-s-m tests

This commit increases the generation frequencies of both the
'genAddBlock' and 'genAddPerasCert' constructions to help producing
denser chains of blocks. This way, some of the events that were
harder to trigger (especially TagSwitchedToShorterChain) are much
more common now:

* Before:
    Tags (5784 in total):
    39.83% TagGetIsValidJust
    29.72% TagChainSelReprocessKeptSelection
    27.92% TagGetIsValidNothing
     2.42% TagChainSelReprocessChangedSelection
     0.10% TagSwitchedToShorterChain

* After:
    Tags (5202 in total):
    38.66% TagGetIsValidJust
    27.87% TagChainSelReprocessKeptSelection
    26.43% TagGetIsValidNothing
     5.71% TagChainSelReprocessChangedSelection
     1.33% TagSwitchedToShorterChain

Author: agustinmista

ouroboros-consensus/test/storage-test/Test/Ouroboros/Storage/ChainDB/StateMachine.hs

@@ -985,9 +985,9 @@ generator ::
 generator loe genBlock m@Model{..} =
   At
     <$> frequency
-      [ (30, genAddBlock)
+      [ (100, genAddBlock)
       , let freq = case loe of
-              LoEDisabled -> 10
+              LoEDisabled -> 100
               -- The LoE does not yet support Peras.
               LoEEnabled () -> 0
          in (freq, genAddPerasCert)