ci: use cargo-llvm-cov to generate code coverage data

The rustc's -Zprofile compiler flag was removed on nightly [1], which
means gcov-style coverage instrumentation is no longer possible.

[1] rust-lang/rust#131829

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

.github/workflows/ci.yaml

@@ -43,31 +43,16 @@ jobs:
 
   test:
     name: Tests and Coverage Report
-    env:
-      holo: rust_ci_github_actions_workflow
-      CARGO_INCREMENTAL: 0
-      RUSTFLAGS: -Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort
-      RUSTDOCFLAGS: -Cpanic=abort
-    permissions:
-      checks: write
-      pull-requests: write
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@nightly
-      - name: Generate test result and coverage report
-        run: |
-          cargo install cargo2junit grcov;
-          cargo test $CARGO_OPTIONS -p holo-bfd -p holo-bgp -p holo-isis -p holo-ldp -p holo-ospf -p holo-rip -- -Z unstable-options --format json | cargo2junit > results.xml;
-          grcov . -s . -t lcov --llvm --ignore-not-existing --ignore "/*" --ignore "holo-*/tests/*" -o lcov.info;
-      - name: Upload test results
-        uses: EnricoMi/publish-unit-test-result-action@v1
-        if: github.event_name != 'pull_request'
-        with:
-          check_name: Test Results
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          files: results.xml
-      - name: Upload to CodeCov
+      - name: Install Rust
+        run: rustup update nightly && rustup default nightly
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo llvm-cov --all-features --codecov --output-path codecov.json -p holo-bfd -p holo-bgp -p holo-isis -p holo-ldp -p holo-ospf -p holo-rip
+      - name: Upload to Codecov
         uses: codecov/codecov-action@v4
         if: github.event_name != 'pull_request'
         with: