[ci] Collect subsystem-benchmarks results and add graphs for them (#3853)

PR adds CI jobs that collect subsystem-benchmarks results and publishes
them to gh-pages.

cc https://github.com/paritytech/ci_cd/issues/934
cc @AndreiEres

.gitlab/pipeline/test.yml

@@ -497,6 +497,12 @@ test-syscalls:
 
 subsystem-regression-tests:
   stage: test
+  artifacts:
+    name: "${CI_JOB_NAME}_${CI_COMMIT_REF_NAME}"
+    when: on_success
+    expire_in: 1 days
+    paths:
+      - charts/
   extends:
     - .docker-env
     - .common-refs