remove any filterable columns when doing a "clear" or "reset" on the filter form.

Also clear out the process initiator.

spiffworkflow-frontend/src/components/ProcessInstanceListTable.tsx

@@ -702,6 +702,14 @@ export default function ProcessInstanceListTable({
     setEndFromTime('');
     setEndToDate('');
     setEndToTime('');
+    setProcessInitiatorSelection(null);
+    setProcessInitiatorText('');
+
+    if (reportMetadata) {
+      reportMetadata.columns = reportMetadata.columns.filter(
+        (column) => !column.filterable
+      );
+    }
   };
 
   const processInstanceReportDidChange = (selection: any, mode?: string) => {