ci: stop carrying forward the dead circleci codecov flag

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

codecov.yaml

@@ -25,6 +25,8 @@ flag_management:
       carryforward: false
     - name: proxy-db-schema-migration
       carryforward: false
+    - name: circleci
+      carryforward: false
 
 component_management:
   individual_components:

codecov.yml

@@ -1,14 +0,0 @@
-coverage:
-  status:
-    patch:
-      default:
-        # only count freshly uploaded coverage, not sessions carried forward
-        # from older commits whose line numbers no longer match the head
-        flag_coverage_not_uploaded_behavior: exclude
-
-flags:
-  circleci:
-    # carried-forward CircleCI sessions come from older commits, so their line
-    # numbers are misaligned with the head and poison the patch status
-    carryforward: false
-    joined: false