Add test to beacon node fallback feature #19144

Job	Run time
Check for 'skip-ci' label	1s
check-msrv	5m 17s
check-code	7m 9s
lockbud	14m 4s
target-branch-check	1s
network-tests	18m 42s
beacon-chain-tests	25m 35s
op-pool-tests	16m 19s
debug-tests-ubuntu	3m 42s
release-tests-ubuntu	4m 51s
release-tests-windows	15m 8s
slasher-tests	3m 49s
basic-simulator-ubuntu	16m 24s
cargo-udeps	7m 16s
cli-check	8m 44s
compile-with-beta-compiler	14m 48s
execution-engine-integration-ubuntu	17s
fallback-simulator-ubuntu	14m 13s
ef-tests-ubuntu	7m 52s
state-transition-vectors-ubuntu	2m 57s
test-suite-success	0s
	3h 7m 9s

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