Small scalability improvements for offchain data sources #9891

Job	Run time
Run integration tests	5m 36s
Run integration tests	5m 36s
Run unit tests	7m 24s
Run unit tests	7m 24s
Build in release mode	1m 50s
Build in release mode	1m 50s
Subgraph Runner integration tests	3m 35s
Subgraph Runner integration tests	3m 27s
Check rustfmt style	5s
Check rustfmt style	5s
Clippy linting	50s
Clippy linting	50s
	38m 32s

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