AP_Mission: `DO_RETURN_PATH_START` limit worst case runtime #43885

Job	Run time
build (stm32f7, chibios, 10)	9m 44s
build (stm32h7, chibios, 10)	9m 3s
build (fmuv2-plane, chibios, 10)	3m 41s
build (periph-build, chibios, 10)	3m 26s
build (iofirmware, chibios, 10)	1m 32s
build (CubeOrange-bootloader, chibios, 10)	53s
build (fmuv3-bootloader, chibios, 10)	49s
build (revo-bootloader, chibios, 10)	47s
build (stm32h7-debug, chibios, 10)	5m 1s
build (fmuv3, chibios, 10)	11m 23s
build (revo-mini, chibios, 10)	8m 59s
build (MatekF405-Wing, chibios, 10)	9m 3s
build (CubeOrange-ODID, chibios, 10)	6m 16s
build (CubeRedPrimary-bootloader, chibios, 10)	1m 7s
build (configure-all, chibios, 10)	10m 51s
build (build-options-defaults-test, chibios, 10)	17m 15s
build (signing, chibios, 10)	5m 35s
build (CubeOrange-PPP, chibios, 10)	4m 47s
build (CubeRed-EKF2, chibios, 10)	4m 38s
build (SOHW, chibios, 10)	8m 6s
build (Pixhawk6X-PPPGW, chibios, 10)	1m 51s
build (new-check, chibios, 10)	10m 30s
	2h 15m 17s

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