CI(codecov): do not notify until all reports are ready (#4136)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Chores**
- Updated the code coverage notification settings to trigger alerts
after 14 builds, improving monitoring of code coverage metrics.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

codecov.yml

@@ -44,3 +44,7 @@ component_management:
       name: i-PI
       paths:
         - source/ipi/**
+codecov:
+  notify:
+    # 12 Python + 2 C++
+    after_n_builds: 14