restore test disabling when the coral authentication file is not readable

CMakeLists.txt

@@ -13,3 +13,8 @@ tdaq_add_executable(rn_ls    src/ls.cpp     LINK_LIBRARIES rn oks_utils Boost::d
 tdaq_add_executable(rn_test  test/test.cpp  LINK_LIBRARIES rn oks_utils NOINSTALL)
 
 add_test(NAME rn_check COMMAND ${TDAQ_RUNNER} ${CMAKE_CURRENT_BINARY_DIR}/rn_test -c nightly_check:atlas_oks_archive:oracle://int8r/tdaq_dev_backup_w -p dummu)
+
+# EXISTS checks for existence and readability of the file
+if(NOT EXISTS "$ENV{CORAL_AUTH_PATH}/authentication.xml")
+  set_tests_properties(rn_check PROPERTIES DISABLED TRUE)
+endif()