Remove `prevOnRamp` from multi onramp #2312

Job	Run time
Check for go-ethereum dependency bump	20s
Check if the job should run	1s
Check images used as test dependencies exist in ECR	0s
Select Versions	0s
Get Latest EVM Implementation's Images	0s
Build Chainlink Image	0s
Prepare Compatibility Matrix	0s
CCIP Compatibility with ${{ matrix.evm_node.visible_name }}	0s
Parse Test Results	0s
Start Slack Thread	0s
Post Test Results	0s
Aggregated test results	0s
	21s

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