Fix build sources (sonic-net#23962)

Fix build sources

Author: tirupatihemanth

scripts/build_mirror_config.sh

@@ -25,7 +25,12 @@ if [ "$ARCHITECTURE" == "armhf" ]; then
     DEFAULT_MIRROR_SECURITY_URLS=http://deb.debian.org/debian-security/
 fi
 
-if [ "$DISTRIBUTION" == "buster" ] || [ "$DISTRIBUTION" == "bullseye" ]; then
+if [ "$DISTRIBUTION" == "buster" ]; then
+    DEFAULT_MIRROR_URLS=http://archive.debian.org/debian/
+    DEFAULT_MIRROR_SECURITY_URLS=http://archive.debian.org/debian-security/
+fi
+
+if [ "$DISTRIBUTION" == "bullseye" ]; then
     DEFAULT_MIRROR_URLS=http://archive.debian.org/debian/
 fi