Drop ctrl-key requirement in "Purge all caches" operation

Related feedback:
- https://www.reddit.com/r/uBlockOrigin/comments/lrcwii/memory_use_in_roaming_profile_in_windows/goq6h4n/

Author: gorhill

src/js/3p-filters.js

@@ -678,7 +678,7 @@ uDom('#ignoreGenericCosmeticFilters').on('change', onFilteringSettingsChanged);
 uDom('#buttonApply').on('click', ( ) => { buttonApplyHandler(); });
 uDom('#buttonUpdate').on('click', ( ) => { buttonUpdateHandler(); });
 uDom('#buttonPurgeAll').on('click', ev => {
-    buttonPurgeAllHandler(ev.ctrlKey && ev.shiftKey);
+    buttonPurgeAllHandler(ev.shiftKey);
 });
 uDom('#lists').on('change', '.listEntry input', onListsetChanged);
 uDom('#lists').on('click', '.listEntry .remove', onRemoveExternalList);