coverage.yml: avoid unnecessary test execution and package installation / come cleanups (#4434)

* coverage.yml: avoid duplicated test execution

* coverage.yml: split test execution and report generation into separate steps

* coverage.yml: split software and Python package installation into separate steps

* coverage.yml: removed unnecessary `libcppunit-dev` installation - library headers are only needed when performing syntax checking

.github/workflows/coverage.yml

@@ -23,22 +23,25 @@ jobs:
       - name: Install missing software on ubuntu
         run: |
           sudo apt-get update
-          sudo apt-get install libxml2-utils
-          sudo apt-get install lcov
-          sudo apt-get install libcppunit-dev
+          sudo apt-get install libxml2-utils lcov
+
+      - name: Install missing Python packages on ubuntu
+        run: |
           python -m pip install pip --upgrade
           python -m pip install lcov_cobertura
 
       - name: Compile instrumented
         run: |
           export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
-          make -j$(nproc) test CXXFLAGS="-g -fprofile-arcs -ftest-coverage" HAVE_RULES=yes
-          
-      - name: Generate coverage report
+          make -j$(nproc) all CXXFLAGS="-g -fprofile-arcs -ftest-coverage" HAVE_RULES=yes
+
+      - name: Run instrumented tests
         run: |
-          rm -rf coverage_report
           ./testrunner
           test/cfg/runtests.sh
+
+      - name: Generate coverage report
+        run: |
           gcov lib/*.cpp -o lib/
           lcov --directory ./ --capture --output-file lcov_tmp.info -b ./
           lcov --extract lcov_tmp.info "$(pwd)/*" --output-file lcov.info