samples/subsys/instrumentation: add missing sample.yaml

This commit adds a missing `sample.yaml` file to the instrumentation
subsystem sample.

Signed-off-by: Filip Kokosinski <[email protected]>

Author: fkokosinski

samples/subsys/instrumentation/sample.yaml

@@ -0,0 +1,7 @@
+sample:
+  name: Instrumentation subsystem sample
+tests:
+  sample.instrumentation:
+    filter: dt_compat_enabled("zephyr,retained-ram")
+    tags: instrumentation
+    build_only: true