[build] Change raw image disk size to 1700MB (#16463)

Maximum RAM availability for NOS to SONiC migration using raw image in Dell S6100 is 1700MB.
Raw images larger than that cannot be used for NOS to SONiC migration.

Author: ArunSaravananBalachandran

onie-image.conf

@@ -37,7 +37,7 @@ OUTPUT_ONIE_IMAGE=target/sonic-$TARGET_MACHINE.bin
 OUTPUT_RAW_IMAGE=target/sonic-$TARGET_MACHINE.raw
 
 ## Raw image size in MB
-RAW_IMAGE_DISK_SIZE=4096
+RAW_IMAGE_DISK_SIZE=1700
 
 ## Output file name for kvm image
 OUTPUT_KVM_IMAGE=target/sonic-$TARGET_MACHINE.img