AP_Scripting: fix mavlink_test.lua test #33906

Job	Run time
build (stm32f7, chibios, 10)	13m 14s
build (stm32h7, chibios, 10)	11m 28s
build (fmuv2-plane, chibios, 10)	4m 58s
build (periph-build, chibios, 10)	14m 1s
build (iofirmware, chibios, 10)	1m 49s
build (CubeOrange-bootloader, chibios, 10)	52s
build (fmuv3-bootloader, chibios, 10)	1m 10s
build (revo-bootloader, chibios, 10)	54s
build (stm32h7-debug, chibios, 10)	6m 20s
build (fmuv3, chibios, 10)	12m 11s
build (revo-mini, chibios, 10)	10m 22s
build (MatekF405-Wing, chibios, 10)	10m 5s
build (CubeOrange-ODID, chibios, 10)	7m 45s
build (CubeRedPrimary-bootloader, chibios, 10)	51s
build (configure-all, chibios, 10)	8m 35s
build (build-options-defaults-test, chibios, 10)	18m 52s
build (signing, chibios, 10)	8m 12s
	2h 11m 39s

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