ci: remove cache key fallback

While having a cache key fallback can be beneficial it also results in increased cache size the currently the cache size almost doubled in size to 2.6Gib because it is never cleaned and results in slower builds.

Author: alan-agius4

.circleci/config.yml

@@ -15,8 +15,7 @@
 #             (Using the tag in not necessary when pinning by ID, but include it anyway for documentation purposes.)
 # **NOTE 2**: If you change the version of the docker images, also change the `cache_key` suffix.
 var_1: &docker_image circleci/node:10.16-browsers@sha256:d2a96fe1cbef51257ee626b5f645e64dade3e886f00ba9cb7e8ea65b4efe8db1
-var_2: &cache_key v8-nguniversal-{{ checksum "yarn.lock" }}-{{ checksum "WORKSPACE" }}-node-10.16
-var_3: &cache_key_fallback v8-nguniversal-
+var_2: &cache_key v1-nguniversal-{{ checksum "yarn.lock" }}-{{ checksum "WORKSPACE" }}-node-10.16
 
 # Workspace initially persisted by the `setup` job.
 # https://circleci.com/docs/2.0/workflows/#using-workspaces-to-share-data-among-jobs
@@ -61,7 +60,6 @@ jobs:
       - restore_cache:
           keys:
             - *cache_key
-            - *cache_key_fallback
       - run: yarn install --frozen-lockfile --non-interactive
       # Reduces ~25mb from being persisted to the workspace
       - run: rm -rf .git