graph: Revert earliest_block off-by-one fix from #6340 #11269

Job	Run time
Clippy linting	1m 52s
Run integration tests	3m 59s
Run unit tests	3m 40s
Build in release mode	1m 41s
Check rustfmt style	19s
Subgraph Runner integration tests	2m 47s
	14m 18s

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