sdk: copy system-qemu.img to system-images.zip

Since init requires system to have partition table
and the original raw system.img does not have it.
system-qemu.img is now created to contain the exact
raw system.img, plus partition table.

When creating the sdk-repo-{host}-system-images.zip
file, using system-qemu.img instead of system.img.

BUG: 64235252

(cherry picked from commit b758d3e8883af526c35ba4b2113eb67921c796f0)

Change-Id: I1dee0767a18c52a62ded6eb0b72a06ab93093783
diff --git a/build/sdk.atree b/build/sdk.atree
index 17c7de6..76c6994 100644
--- a/build/sdk.atree
+++ b/build/sdk.atree
@@ -235,7 +235,7 @@
 ##############################################################################
 
 # System images + Kernel
-system.img                                 system-images/${PLATFORM_NAME}/${TARGET_CPU_ABI}/system.img
+system-qemu.img                                 system-images/${PLATFORM_NAME}/${TARGET_CPU_ABI}/system.img
 ramdisk.img                                system-images/${PLATFORM_NAME}/${TARGET_CPU_ABI}/ramdisk.img
 userdata.img                               system-images/${PLATFORM_NAME}/${TARGET_CPU_ABI}/userdata.img
 system/build.prop                          system-images/${PLATFORM_NAME}/${TARGET_CPU_ABI}/build.prop