DefaultRefFilter#getTaggableRefs: remove presizing

Since we're filtering out the refs/changes/ prefix, the presized array
is likely too large, leading to extra memory/garbage overhead.

Change-Id: If28d2d4125923fce6b67de728a353ecd6e0be7de

java/com/google/gerrit/server/permissions/DefaultRefFilter.java

@@ -326,7 +326,7 @@ class DefaultRefFilter {
                       && !r.getName().startsWith(RefNames.REFS_TAGS)
                       && !r.isSymbolic()
                       && !r.getName().equals(RefNames.REFS_CONFIG))
-          .collect(toCollection(() -> new ArrayList<>(allRefs.size())));
+          .collect(Collectors.toList());
     } catch (IOException e) {
       throw new PermissionBackendException(e);
     }