docker/groovy: Fix coverage reports for tumbleweed

- Run lcov_to_cobertura with python3 explicitly
- Install missing lcov dependency perl-JSON

dockerfiles/tumbleweed.docker

@@ -25,6 +25,7 @@ RUN zypper refresh && \
     zypper install -y nano && \
     zypper install -y vim && \
     zypper install -y python3-pytest && \
+    zypper install -y perl-JSON && \
     useradd -u 30996 msk_jenkins && \
     ln -sfn /usr/lib64/libzmq.so.5 /usr/lib64/libzmq.so.3
 

vars/helper.groovy

@@ -341,7 +341,7 @@ for VAR in \${JOB_VARIABLES} \${TEST_VARIABLES}; do
    export \\`eval echo \\\${VAR}\\`
 done
 make coverage || true
-/common/lcov_cobertura-1.6/lcov_cobertura/lcov_cobertura.py coverage.info || true
+python3 /common/lcov_cobertura-1.6/lcov_cobertura/lcov_cobertura.py coverage.info || true
 
 cp -r coverage_html ${WORKSPACE} || true
 cp -r coverage.xml ${WORKSPACE} || true