codecov: remove notifications until we can address false reporting

I don't think we're quite ready for codecov reporting on every PR. The initial report seems to work fine, but there are various issues that result in bogus reporting when additional commits are added or after a rebase.

codecov.yml

@@ -1,32 +0,0 @@
-codecov:
-  require_ci_to_pass: yes
-  notify:
-    after_n_builds: 5
-    wait_for_ci: yes
-
-coverage:
-  status:
-    project:
-      default:
-        target: auto
-        threshold: 5%
-        base: auto
-        only_pulls: true
-
-parsers:
-  gcov:
-    branch_detection:
-      conditional: yes
-      loop: yes
-      method: no
-      macro: no
-
-comment:
-  layout: "reach,diff,flags,tree"
-  behavior: default
-  require_changes: yes
-
-ignore:
-  - "src/examples"
-  - "src/modules/attitude_estimator_q"
-  - "src/modules/local_position_estimator"