fix(users/flokli/nixos-tvix-cache): bump trace size limit

We produce traces bigger than what tempo accepts by default, causing
traces to be rejected with TRACE_TOO_LARGE and to then be incomplete.

Bump the max size.

Change-Id: I8caa245d14db683853485ee5625c9662ea51ce29
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12926
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

users/flokli/nixos/nixos-tvix-cache/monitoring.nix

@@ -31,8 +31,9 @@ in
         local.path = "/var/lib/tempo/blocks";
       };
       usage_report.reporting_enabled = false;
-      # 10x the default
+      # bump defaults
       overrides.defaults.ingestion.max_traces_per_user = 10000 * 10;
+      overrides.defaults.global.max_bytes_per_trace = 500 * 1000 * 1000;
     };
   };