ci: disable session telemetry in all GitHub workflows

apps/cli/cordis.yml now bakes in the production OTLP endpoint; CI boots of
the web composition (e2e, snapshots, built smokes) must not stream test
sessions there. DSH_TELEMETRY_DISABLED=1 at the workflow level disables
the telemetry row before its load-time url validation; the telemetry e2e
still runs — it overrides the variable to empty for its child process and
points DSH_TELEMETRY_OTLP_URL at its in-test collector.

.github/workflows/expected-filenames.yml

@@ -10,6 +10,11 @@ on:
 permissions:
   contents: read
 
+env:
+  # CI runs must never report to the production telemetry endpoint baked
+  # into apps/cli/cordis.yml (AppCLIEntry disables the row when set).
+  DSH_TELEMETRY_DISABLED: '1'
+
 jobs:
   expected-filenames:
     name: no golden filenames