Hook go-licenses into tidy again (#21353)

Running it as part of the build is really unnecessary because we have a
valid output file in the repo and assuming go dependencies do not change
unless go.mod also changes, tidy really is the best target to run the
license generation after.

Also, regenerate the file as I missed to do so during the chroma update,
and mark all json files in assets as generated.

.gitattributes

@@ -1,5 +1,6 @@
 * text=auto eol=lf
 *.tmpl linguist-language=Handlebars
+/assets/*.json linguist-generated
 /public/vendor/** -text -eol linguist-vendored
 /vendor/** -text -eol linguist-vendored
 /web_src/fomantic/build/** linguist-generated