Merge pull request #210 from mulesoft/MULE-7149

MULE-7149 - fix flow variable propagation between flows using flow-ref(cherry picked from commit 4ec607bb3f8fba7b821415f9bf2e49aeffb215f7)
Merge pull request #217 from mulesoft/MULE-7149

MULE-7149 - Fixing test failures - Making flow-ref to use the same sessi...(cherry picked from commit 1965727375edf3ce19b153c52ba022a0e8afbfc2)