Disable thermal collector on indri Alloy

The thermal collector fails on macOS M1 with "no CPU power status has
been recorded" - this hardware doesn't expose power metrics in a way
the collector understands.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ansible/roles/alloy/templates/config.alloy.j2

@@ -6,6 +6,9 @@
 
 // System metrics exporter (replaces node_exporter)
 prometheus.exporter.unix "system" {
+  // Disable collectors that don't work on macOS
+  disable_collectors = ["thermal"]
+
   textfile {
     directory = "{{ alloy_textfile_dir }}"
   }