rebuilderd: bump max allowed report upload to 200M

The /api/v0/build/report endpoint has received POSTs up to 161M so far
this year (2022). In 2021 there had been POSTs of sizes up to 404M and
up to 814M for 2020. Multiple hundreds of MB seem a bit excessive, but
we should be able to do up to 200M.

roles/rebuilderd/templates/nginx.d.conf.j2

@@ -53,7 +53,7 @@ server {
     }
 
     location = /api/v0/build/report {
-        client_max_body_size 25M;
+        client_max_body_size 200M;
         proxy_set_header    X-Real-IP          $remote_addr;
         proxy_pass http://127.0.0.1:8484;
     }