disable testing as all tests are commented out anyway

[mikaelarguedas]

@nuclearsandwich FYI this should fix the currently failing jobs

[nuclearsandwich]

I'm not sure if this is the "right" way to fix this but I'm happy to revisit post-release.

[mikaelarguedas]

This was how it was in ardent, I must have messed up my rebase and reenabled this but as the tests are disabled

cartographer_ros/cartographer_ros/CMakeLists.txt

Lines 86 to 95 in 249fdcd

	# # Override Catkin's GTest configuration to use GMock.
	# set(GTEST_FOUND TRUE)
	# set(GTEST_INCLUDE_DIRS ${GMOCK_INCLUDE_DIRS})
	# set(GTEST_LIBRARIES ${GMOCK_LIBRARIES})
	# file(GLOB_RECURSE ALL_SRCS "*.cc" "*.h")
	# file(GLOB_RECURSE ALL_TESTS "*_test.cc")
	# file(GLOB_RECURSE ALL_EXECUTABLES "*_main.cc")
	# list(REMOVE_ITEM ALL_SRCS ${ALL_TESTS})
	# list(REMOVE_ITEM ALL_SRCS ${ALL_EXECUTABLES})

there is no point in enabling testing.

When we actually upgrade to the new cartographer (1.0.0) the problem should go away but that'll be for another day