Give up on codecov

v4 of the action seems to be much more restrictive in what can upload
coveage. I'll miss this (the historic view of coverage was nice!), but
not worth trying to get working again.

We also stop running client tests. These break so often, we only really
ran them for code coverage reasons.

.github/workflows/main-ci.yml

@@ -50,11 +50,6 @@ jobs:
     - name: 🧪 Run integration tests
       run: ./gradlew runGametest
 
-    - name: 🧪 Run client tests
-      run: ./gradlew runGametestClient # Not checkClient, as no point running rendering tests.
-      # These are a little flaky on GH actions: its useful to run them, but don't break the build.
-      continue-on-error: true
-
     - name: 🧪 Parse test reports
       run: ./tools/parse-reports.py
       if: ${{ failure() }}
@@ -71,9 +66,6 @@ jobs:
         name: CC-Tweaked
         path: ./jars
 
-    - name: 📤 Upload coverage
-      uses: codecov/codecov-action@v4
-
   build-core:
     strategy:
       fail-fast: false