Use common observation utility functions. (#2141) #9408

Job	Run time
base-tests (./cli)	2m 48s
base-tests (./envision)	3m 23s
benchmark (e10_drive)	3m 27s
base-tests (./smarts/core --nb-exec-timeout 65536 --ignore=./smarts/core/tests/test_notebook.py)	21m 7s
examples-rl (e10_drive)	5m 10s
base-tests (./smarts/env --ignore=./smarts/env/tests/test_rllib_hiway_env.py)	7m 15s
examples-rl (e11_platoon)	3m 3s
benchmark (e11_platoon)	2m 15s
base-tests (./smarts/env/tests/test_rllib_hiway_env.py)	3m 1s
base-tests (./smarts/sstudio)	2m 50s
base-tests (./smarts/ray)	3m 1s
base-tests (./examples/tests/test_examples.py)	4m 46s
	1h 2m 6s

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