test(store/v2): use pebbledb in store tests

Author: robert-zaremba

server/v2/testdata/config.toml

@@ -40,7 +40,7 @@ moniker = "aurn-node"
 # * badgerdb (uses github.com/dgraph-io/badger)
 #   - EXPERIMENTAL
 #   - use badgerdb build tag (go build -tags badgerdb)
-db_backend = "goleveldb"
+db_backend = "pebbledb"
 
 # Database directory
 db_dir = "data"