[test] Add test manifest for the nightly build

Use the same test manifest for the development and nightly
coverage CI builds. Add manifest for the nightly build by
creating a symbolic link to the existing manifest.

circle.yml

@@ -671,7 +671,7 @@ jobs:
           command: |
             /tmp/attach/install/linux-gcc8-release/bin/mbgl-render-test-runner -u rebaseline -p metrics/binary-size.json
       - run:
-          name: 'Matrics Baselines'
+          name: 'Metrics Baselines'
           command: |
             cp -r /tmp/attach/metrics .
             git add -A && git diff --staged --exit-code | tee baselines.patch

metrics/linux-gcc8-debug-coverage-nightly-style.json

@@ -0,0 +1 @@
+linux-gcc8-debug-coverage-style.json