splitstore: set badger as the default default markset type

[vyzo]

On top of #8008.

Sets badger as the default markset type, so that we can work out of the box if we have <40G of RAM.

[codecov]

Codecov Report

Merging #8034 (0ad1f0e) into feat/splitstore-sortless-compaction (049b489) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@                           Coverage Diff                           @@
##           feat/splitstore-sortless-compaction    #8034      +/-   ##
=======================================================================
- Coverage                                39.20%   39.15%   -0.06%     
=======================================================================
  Files                                      662      662              
  Lines                                    71925    71925              
=======================================================================
- Hits                                     28201    28160      -41     
- Misses                                   38839    38881      +42     
+ Partials                                  4885     4884       -1     

Impacted Files	Coverage Δ
node/config/def.go	97.46% <100.00%> (ø)
markets/loggers/loggers.go	88.88% <0.00%> (-11.12%)	⬇️
extern/storage-sealing/sector_state.go	92.30% <0.00%> (-7.70%)	⬇️
chain/actors/builtin/miner/diff.go	52.94% <0.00%> (-5.89%)	⬇️
chain/stmgr/execute.go	86.95% <0.00%> (-4.35%)	⬇️
chain/messagepool/repub.go	51.61% <0.00%> (-4.31%)	⬇️
chain/stmgr/call.go	67.87% <0.00%> (-3.64%)	⬇️
extern/storage-sealing/states_replica_update.go	37.14% <0.00%> (-3.58%)	⬇️
extern/storage-sealing/states_failed.go	0.00% <0.00%> (-3.39%)	⬇️
chain/sub/incoming.go	54.43% <0.00%> (-3.38%)	⬇️
... and 18 more

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