Coverage tweaks

.codecov.yml

@@ -0,0 +1,19 @@
+codecov:
+  notify:
+    # Keep this in sync with the number of CI jobs uploading coverage.
+    after_n_builds: 2
+coverage:
+  status:
+    project:
+      default:
+        informational: true
+    patch:
+      default:
+        informational: true
+    changes:
+      default:
+        informational: true
+
+comment:
+  layout: "header, diff, changes, tree"
+  behavior: default