[ci.yaml] Add linux benchmarks, add enabled branches (#27405)

Author: Casey Hillers

.ci.yaml

@@ -7,6 +7,9 @@
 #  * https://github.com/flutter/cocoon/blob/master/CI_YAML.md
 enabled_branches:
   - master
+  - dev
+  - beta
+  - stable
 
 platform_properties:
   linux:
@@ -66,6 +69,17 @@ targets:
     timeout: 60
     scheduler: luci
 
+  - name: Linux Benchmarks
+    builder: Linux Benchmarks
+    enabled_branches:
+      - master
+    recipe: engine/engine_metrics
+    presubmit: false
+    properties:
+      build_host: "true"
+    timeout: 60
+    scheduler: luci
+
   - name: Linux Fuchsia
     builder: Linux Fuchsia
     recipe: engine