CI: Build custom image for N1SDP optee-xtest

Build a custom N1SDP image with only optee-xtests as part of the image. A fresh custom image build is necessary to include the relevant test suite for running the xtests.

Signed-off-by: Anusmita Dutta Mazumder <anusmita.duttamazumder@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

.gitlab-ci.yml

@@ -154,6 +154,7 @@ n1sdp:
   parallel:
     matrix:
       - TS: [none, n1sdp-ts]
+      - OPTEE: [none, n1sdp-optee]
 
 qemu-generic-arm64:
   extends: .build

ci/n1sdp-optee.yml

@@ -0,0 +1,12 @@
+header:
+  version: 14
+
+# Config specific for the optee-xtests
+local_conf_header:
+  optee-test: |
+    # Include ARM FFA
+    MACHINE_FEATURES:append = " arm-ffa"
+    # Include trusted services
+    TEST_SUITES:append = " trusted_services"
+    # Include Optee xtests
+    IMAGE_INSTALL:append = " optee-test"