Mark `/templates/swagger/v1_json.tmpl` as generated file (#24306)

.gitattributes

@@ -3,6 +3,7 @@
 /assets/*.json linguist-generated
 /public/img/svg/*.svg linguist-generated
 /public/vendor/** -text -eol linguist-vendored
+/templates/swagger/v1_json.tmpl linguist-generated
 /vendor/** -text -eol linguist-vendored
 /web_src/fomantic/build/** linguist-generated
 /web_src/js/vendor/** -text -eol linguist-vendored