openharmony-standard-3.0: Start appspawn service after samgr

This mofifies the appspawn service to start after the samgr one with a 2
seconds delay.

Signed-off-by: Thierry Escande <thierry.escande@huawei.com>

recipes-openharmony/openharmony/files/appspawn.service

 [Unit]
 Description=OpenHarmony Appspawn service
-Requires=hilogd.service
+Requires=samgr.service
+After=samgr.service
 
 [Service]
 Type=exec
+# Delay execution by 2 secs after samgr.service
+ExecStartPre=/bin/sleep 2
 ExecStartPre=mkdir -p /data/app
 ExecStart=/usr/bin/appspawn