Deduplicate extra network preview-search code

modules/ui_extra_networks_checkpoints.py

@@ -1,7 +1,6 @@
 import html
 import json
 import os
-import urllib.parse
 
 from modules import shared, ui_extra_networks, sd_models
 
@@ -17,18 +16,10 @@ class ExtraNetworksPageCheckpoints(ui_extra_networks.ExtraNetworksPage):
         checkpoint: sd_models.CheckpointInfo
         for name, checkpoint in sd_models.checkpoints_list.items():
             path, ext = os.path.splitext(checkpoint.filename)
-            previews = [path + ".png", path + ".preview.png"]
-
-            preview = None
-            for file in previews:
-                if os.path.isfile(file):
-                    preview = self.link_preview(file)
-                    break
-
             yield {
                 "name": checkpoint.name_for_extra,
                 "filename": path,
-                "preview": preview,
+                "preview": self._find_preview(path),
                 "search_term": self.search_terms_from_path(checkpoint.filename) + " " + (checkpoint.sha256 or ""),
                 "onclick": '"' + html.escape(f"""return selectCheckpoint({json.dumps(name)})""") + '"',
                 "local_preview": path + ".png",