Fix for list_comments test

list_comments with by_permlink takes two arguments, 4 were provided.

hivemind/pyrest_tests/benchmarks/database_api_benchmark.yaml

@@ -26,7 +26,7 @@
     - name: "list_comments"
     - variable_binds:
       - method: "list_comments"
-      - args: '{"start":["steemit","firstpost","",""], "limit":10, "order":"by_permlink"}'
+      - args: '{"start":["steemit","firstpost"], "limit":10, "order":"by_permlink"}'
     - <<: *base_benchmark
   
   - benchmark:

hivemind/pyrest_tests/full_sync/database_api/database_api_test.yaml

@@ -24,7 +24,7 @@
   - name: "list_comments"
   - variable_binds:
     - method: "list_comments"
-    - args: '{"start":["steemit","firstpost","",""], "limit":10, "order":"by_permlink"}'
+    - args: '{"start":["steemit","firstpost"], "limit":10, "order":"by_permlink"}'
   - <<: *base_test
 
 - test: