Update search version after attribution removed from Bing

Fixes brave/brave-browser#21085

Author: bsclifton

components/search_engines/brave_prepopulated_engines.cc

@@ -12,7 +12,7 @@ namespace TemplateURLPrepopulateData {
 
 // IMPORTANT! Make sure to bump this value if you make changes to the
 // engines below or add/remove engines.
-const int kBraveCurrentDataVersion = 17;
+const int kBraveCurrentDataVersion = 18;
 // DO NOT CHANGE THIS ONE. Used for backfilling kBraveDefaultSearchVersion.
 const int kBraveFirstTrackedDataVersion = 6;