Add linux license engine v2 build. (#41797)

This adds the initial configuration and its builder as bringup.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: godofredoc

.ci.yaml

@@ -297,6 +297,14 @@ targets:
       release_build: "true"
       config_name: linux_android_debug_engine
 
+  - name: Linux linux_license
+    bringup: true
+    recipe: engine_v2/builder
+    timeout: 60
+    properties:
+      release_build: "true"
+      config_name: linux_license
+
   - name: Linux linux_web_engine
     recipe: engine_v2/engine_v2
     timeout: 60

ci/builders/standalone/linux_license.json

@@ -0,0 +1,17 @@
+{
+    "drone_dimensions": [
+        "device_type=none",
+        "os=Linux"
+    ],
+    "cas_archive": false,
+    "gclient_variables": {
+        "download_android_deps": false
+    },
+    "name": "licenses",
+    "tests": [
+        {
+            "name": "licenses check",
+            "script": "flutter/ci/licenses.sh"
+        }
+    ]
+}