core-fellowship: allow infinite demotion period (#2828)

.gitlab/pipeline/test.yml

@@ -238,6 +238,8 @@ test-deterministic-wasm:
 
 cargo-check-benches:
   stage: test
+  artifacts:
+    expire_in: 10 days
   variables:
     CI_JOB_NAME: "cargo-check-benches"
   extends:
@@ -303,13 +305,10 @@ node-bench-regression-guard:
       artifacts: true
   variables:
     CI_IMAGE: "paritytech/node-bench-regression-guard:latest"
-    # current git limit is 20, set to 100 to avoid failures (gitlab removes old artifacts)
-    GIT_DEPTH: 100
-    GIT_STRATEGY: fetch
   before_script: [""]
   script:
     - if [ $(ls -la artifacts/benches/ | grep master | wc -l) == 0 ]; then
-      echo "Couldn't find master artifacts, consider increasing GIT_LIMIT variable";
+      echo "Couldn't find master artifacts";
       exit 1;
       fi
     - echo "------- IMPORTANT -------"