DEV: Limit re-use of bundler/yarn caches in CI (#24256)

Using restore-keys means we will always use an old cache, and then add more dependencies to it. This leads to the cache growing over time and becoming increasingly slow. Instead, we should rebuild the cache from scratch each time our dependencies change.

.github/workflows/tests.yml

@@ -80,8 +80,7 @@ jobs:
         uses: actions/cache@v3
         with:
           path: vendor/bundle
-          key: ${{ runner.os }}-${{ matrix.ruby }}-gem-${{ hashFiles('**/Gemfile.lock') }}
-          restore-keys: ${{ runner.os }}-${{ matrix.ruby }}-gem-
+          key: ${{ runner.os }}-${{ matrix.ruby }}-gem-${{ hashFiles('**/Gemfile.lock') }}-cachev2
 
       - name: Setup gems
         run: |
@@ -101,8 +100,7 @@ jobs:
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
-          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
-          restore-keys: ${{ runner.os }}-yarn-
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}-cachev2
 
       - name: Yarn install
         run: yarn install --frozen-lockfile
@@ -307,8 +305,7 @@ jobs:
         id: yarn-cache
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
-          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
-          restore-keys: ${{ runner.os }}-yarn-
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}-cachev2
 
       - name: Yarn install
         working-directory: ./app/assets/javascripts/discourse