Migrate ramdisk_node_list configuration to Android.bp

Removed the hardcoded assignment of `RAMDISK_NODE_LIST` in
`build/core/Makefile`. Instead, a filegroup definition in Android.bp is
now used to manage `ramdisk_node_list` and its export to the make
variable. This change enhances flexibility and simplifies the build
process by eliminating the need for a fixed installation path.

Bug: 359423289
Test: m -j $(PRODUCT_OUT)/ramdisk.img
Change-Id: I5aea108d426a615fa951c368c16f7cdea73252b1
diff --git a/core/Makefile b/core/Makefile
index 96588e3..9c85fbb 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1267,9 +1267,8 @@
 
 endif
 
-
+# The value of RAMDISK_NODE_LIST is defined in system/core/rootdir/Android.bp.
 # This file contains /dev nodes description added to the generic ramdisk
-RAMDISK_NODE_LIST := $(PRODUCT_OUT)/ramdisk_node_list
 
 # We just build this directly to the install location.
 INSTALLED_RAMDISK_TARGET := $(BUILT_RAMDISK_TARGET)