Codecov: post comment only if there are coverage changes AND 2 reports have been received

We upload coverage for unit tests and integration tests separately.
This should prevent showing incorrect info and reduce spam

[skip ci]
[CI SKIP]

Signed-off-by: Álvaro Brey <alvaro.brey@nextcloud.com>

.codecov.yml

@@ -17,6 +17,8 @@ coverage:
 comment:
   layout: "header, diff, changes, uncovered, tree"
   behavior: default
+  require_changes: true
+  after_n_builds: 2
 
 github_checks:
     annotations: false