agentlog: fix race condition in tests #9237

Job	Run time
packages (buildjet-4vcpu-ubuntu-2204-arm, arm64)	4m 13s
packages (buildjet-4vcpu-ubuntu-2004, amd64)	5m 30s
packages (buildjet-4vcpu-ubuntu-2004, riscv64)	2m 42s
eve (arm64, xen, generic)	7m 6s
eve (arm64, kvm, generic)	7m 6s
eve (amd64, xen, generic)	9m 49s
eve (amd64, kvm, generic)	8m 53s
eve (amd64, kubevirt, generic)	12m 11s
eve (riscv64, mini, generic)	3m 9s
eve (amd64, kvm, rt)	7m 49s
eve (arm64, kvm, nvidia)	12m 17s
eve (arm64, kvm, imx8mp_pollux)	7m 30s
eve (arm64, kvm, imx8mp_epc_r3720)	9m 42s
	1h 37m 57s

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