remove files under test directory from coverage report

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22212)

.github/workflows/coveralls.yml

@@ -64,7 +64,13 @@ jobs:
     - name: make test
       run: make test HARNESS_JOBS=${HARNESS_JOBS:-4} TESTS='-test_external_krb5'
     - name: generate coverage info
-      run: lcov -d . -c -o ./lcov.info
+      run: lcov -d . -c \
+             --exclude "${PWD}/test/*" \
+             --exclude "${PWD}/test/helpers/*" \
+             --exclude "${PWD}/test/testutil/*" \
+             --exclude "${PWD}/fuzz/*" \
+             --exclude "/usr/include/*" \
+              -o ./lcov.info
     - name: Coveralls upload
       uses: coverallsapp/github-action@v2.2.3
       with: