Refactor init.environ.rc to append than replace

Bug: 353429422
Test: boot
Change-Id: Ibd432fa39fc75f8b49ae26fbc6b74f11fb3f771d
diff --git a/rootdir/init.environ.rc.in b/rootdir/init.environ.rc.in
index 7ba1f46..9249270 100644
--- a/rootdir/init.environ.rc.in
+++ b/rootdir/init.environ.rc.in
@@ -10,8 +10,5 @@
     export ANDROID_TZDATA_ROOT /apex/com.android.tzdata
     export EXTERNAL_STORAGE /sdcard
     export ASEC_MOUNTPOINT /mnt/asec
-    %EXPORT_GLOBAL_ASAN_OPTIONS%
-    %EXPORT_GLOBAL_GCOV_OPTIONS%
-    %EXPORT_GLOBAL_CLANG_COVERAGE_OPTIONS%
-    %EXPORT_GLOBAL_HWASAN_OPTIONS%
-    %EXPORT_GLOBAL_SCUDO_ALLOCATION_RING_BUFFER_SIZE%
+    # Additional environment variables will be appended here during build (see Android.bp).
+    # DO NOT ADD additional sections like 'on <event>' here.