Update dashboard parameters (#470)

This PR addresses the change proposed here:
cowprotocol/dune-queries#102
that adds a blockchain parameter in the main rewards dashboard.

src/fetch/dune.py

@@ -107,16 +107,14 @@ def get_period_slippage(self, job_id: Optional[str] = None) -> list[DuneRecord]:
         Executes & Fetches results of slippage query per solver for specified accounting period.
         Returns a class representation of the results as two lists (positive & negative).
         """
-        params = self._period_params()
+        params = self._network_and_period_params()
         # trigger dashboard update
         self.dune.execute(
             self._parameterized_query(QUERIES["DASHBOARD_SLIPPAGE"], params=params)
         )
 
         return self._get_query_results(
-            self._parameterized_query(
-                QUERIES["PERIOD_SLIPPAGE"], params=self._network_and_period_params()
-            ),
+            self._parameterized_query(QUERIES["PERIOD_SLIPPAGE"], params=params),
             job_id,
         )