Disable codecov's require_ci_to_pass mode

despite our attempts to fix it with the `after_n_builds` setting, it's still showing spurious fluctuations due to sometimes running elasticsearch tests and sometimes not

codecov.yml

@@ -1,4 +1,5 @@
 codecov:
   notify:
     after_n_builds: 10
+    require_ci_to_pass: no
 comment: off