horizon: Clean up integration test variables (#5288) #6

Job	Run time
Test (and push) verify-range image	2m 5s
Test and push the Ledger Exporter images	1m 11s
Integration tests (ubuntu-20.04, 1.21, 12, 20)	47m 17s
Integration tests (ubuntu-20.04, 1.21, 12, 21)	46m 27s
Integration tests (ubuntu-20.04, 1.21, 16, 20)	46m 46s
Integration tests (ubuntu-20.04, 1.21, 16, 21)	46m 47s
Integration tests (ubuntu-20.04, 1.22, 12, 20)	46m 29s
Integration tests (ubuntu-20.04, 1.22, 12, 21)	46m 50s
Integration tests (ubuntu-20.04, 1.22, 16, 20)	46m 4s
Integration tests (ubuntu-20.04, 1.22, 16, 21)	46m 27s
Integration tests (ubuntu-22.04, 1.21, 12, 20)	45m 56s
Integration tests (ubuntu-22.04, 1.21, 12, 21)	46m 2s
Integration tests (ubuntu-22.04, 1.21, 16, 20)	46m 23s
Integration tests (ubuntu-22.04, 1.21, 16, 21)	46m 43s
Integration tests (ubuntu-22.04, 1.22, 12, 20)	47m 36s
Integration tests (ubuntu-22.04, 1.22, 12, 21)	45m 54s
Integration tests (ubuntu-22.04, 1.22, 16, 20)	46m 2s
Integration tests (ubuntu-22.04, 1.22, 16, 21)	46m 0s
	12h 26m 59s

Provide feedback