CI: consolidate target in meta-zephyr.yml

Set a default target in meta-zephyr.yml to avoid duplication now that
most configurations build zephyr-kernel-test-all.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

ci/meta-zephyr.yml

@@ -8,3 +8,6 @@ repos:
     url: https://git.yoctoproject.org/git/meta-zephyr
     layers:
       meta-zephyr-core:
+
+target:
+  - zephyr-kernel-test-all

ci/microbit-v1.yml

@@ -9,6 +9,3 @@ local_conf_header:
     ZEPHYRTESTS:remove = "common"
 
 machine: microbit-v1
-
-target:
-  - zephyr-kernel-test-all

ci/qemu-cortex-a53.yml

@@ -7,6 +7,3 @@ header:
 # FIXME - testimage fails all tests currently, but all the tests build
 
 machine: qemu-cortex-a53
-
-target:
-  - zephyr-kernel-test-all

ci/qemu-cortex-m3.yml

@@ -16,6 +16,3 @@ local_conf_header:
     ZEPHYRTESTS:remove = "context pending sleep"
 
 machine: qemu-cortex-m3
-
-target:
-  - zephyr-kernel-test-all

ci/qemu-cortex-r5.yml

@@ -9,6 +9,3 @@ local_conf_header:
     ZEPHYRTESTS:remove = "common poll sleep queue device"
 
 machine: qemu-cortex-r5
-
-target:
-  - zephyr-kernel-test-all