tools/ci.sh: Remove one build from zephyr CI to speed it up.

The zephyr CI takes the most time out of all CI jobs, so remove the
standard qemu_x86 build to speed it up.  The remaining builds should still
cover enough cases to catch errors.

Signed-off-by: Damien George <damien@micropython.org>

tools/ci.sh

@@ -691,7 +691,6 @@ function ci_zephyr_install {
 
 function ci_zephyr_build {
     docker exec zephyr-ci west build -p auto -b qemu_x86 -- -DCONF_FILE=prj_minimal.conf
-    docker exec zephyr-ci west build -p auto -b qemu_x86
     docker exec zephyr-ci west build -p auto -b frdm_k64f
     docker exec zephyr-ci west build -p auto -b mimxrt1050_evk
     docker exec zephyr-ci west build -p auto -b nucleo_wb55rg # for bluetooth