Node/Aptos: Don't replay old observation on startup #324

Job	Run time
e2e-tests (ictest-cancel-upgrade)	3m 33s
e2e-tests (ictest-cancel-upgrade)	3m 33s
e2e-tests (ictest-upgrade)	9m 10s
e2e-tests (ictest-upgrade)	9m 10s
e2e-tests (ictest-wormchain)	6m 47s
e2e-tests (ictest-wormchain)	6m 47s
e2e-tests (ictest-ibc-receiver)	31m 36s
e2e-tests (ictest-ibc-receiver)	10m 6s
e2e-tests (ictest-cw-wormhole)	8m 29s
e2e-tests (ictest-cw-wormhole)	8m 29s
	1h 37m 40s

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