fix(nginx): _assets should rewrite to _static/sentry/dist

Our default fallback, `_assets`, assumes we use a CDN which is not the case on self-hosted. This patch adds a stop-gap fix for front-end URLs asking for this path.

Should fix #3479 and #3470.

Author: BYK

nginx.conf

@@ -98,6 +98,9 @@ http {
 		location / {
 			proxy_pass http://sentry;
 		}
+		location /_assets/ {
+			proxy_pass http://sentry/_static/dist/sentry/;
+		}
 		location /_static/ {
 			proxy_pass http://sentry;
 			proxy_hide_header Content-Disposition;