add disableParamFiltering() to both test_generalstate_json and test_blockchain_json

disableParamFiltering() is called in test_all, so its ok when
called via test_all. but when test_generalstate_json or
test_blockchain_json is called independently, and we are using
command line switch, the default param handler from std/unittest
will interfere. hence need to disable it.

tests/test_blockchain_json.nim

@@ -795,6 +795,7 @@ when isMainModule:
       echo message
       quit(QuitSuccess)
 
+  disableParamFiltering()
   blockchainJsonMain(true)
 
 # lastBlockHash -> every fixture has it, hash of a block header

tests/test_generalstate_json.nim

@@ -231,4 +231,6 @@ when isMainModule:
     if len(message) > 0:
       echo message
       quit(QuitSuccess)
+
+  disableParamFiltering()
   generalStateJsonMain(true)