[DOP-29475] Fix filenameTemplate pattern

Author: dolfinus

src/entities/file/ui/FileNameTemplate/constants.ts

@@ -1,3 +1,3 @@
-/** Regexp to filename template, which must include `{extension}` and `{index}` placeholder (e.g. qwerty_{index}.{extension}) */
-export const FILE_NAME_TEMPLATE_PATTERN =
-  /^(?=.*\{index\})(?=.*\{extension\})([\w\d.\-]*\{(?:index|extension|run_created_at|run_id)\}[\w\d.\-]*)*$/iu;
+/** Regexp to filename template */
+export const FILE_NAME_TEMPLATE_PATTERN = 
+  /^[\w.-]*(\{index\}){0,1}[\w.-]*(\{run_id\}|\{run_created_at\})[\w.-]*(\{index\}){0,1}[\w.-]*\{extension\}$/iu;