AC_Autotune: Clean up Multi Variables and non functional changes #40626

Job	Run time
build (stm32f7, chibios, 10)	7m 30s
build (stm32h7, chibios, 10)	6m 33s
build (fmuv2-plane, chibios, 10)	4m 17s
build (periph-build, chibios, 10)	5m 28s
build (iofirmware, chibios, 10)	3m 39s
build (CubeOrange-bootloader, chibios, 10)	3m 3s
build (fmuv3-bootloader, chibios, 10)	3m 12s
build (revo-bootloader, chibios, 10)	2m 56s
build (stm32h7-debug, chibios, 10)	5m 1s
build (fmuv3, chibios, 10)	9m 36s
build (revo-mini, chibios, 10)	7m 23s
build (MatekF405-Wing, chibios, 10)	7m 44s
build (CubeOrange-ODID, chibios, 10)	5m 42s
build (CubeRedPrimary-bootloader, chibios, 10)	2m 58s
build (configure-all, chibios, 10)	12m 56s
build (build-options-defaults-test, chibios, 10)	13m 1s
build (signing, chibios, 10)	5m 19s
build (CubeOrange-PPP, chibios, 10)	5m 3s
build (SOHW, chibios, 10)	6m 52s
build (Pixhawk6X-PPPGW, chibios, 10)	3m 27s
build (new-check, chibios, 10)	8m 21s
	2h 10m 1s

Provide feedback