Rename product_services to system_ext

Bug: 134359158
Test: build and check if system_ext.img is created
Change-Id: I67f2e95dd29eac6a28e07e24ea973d3a134c3bfc

tools/releasetools/merge_target_files.py

@@ -146,8 +146,8 @@ DEFAULT_FRAMEWORK_MISC_INFO_KEYS = (
     'avb_system_rollback_index_location',
     'avb_product_hashtree_enable',
     'avb_product_add_hashtree_footer_args',
-    'avb_product_services_hashtree_enable',
-    'avb_product_services_add_hashtree_footer_args',
+    'avb_system_ext_hashtree_enable',
+    'avb_system_ext_add_hashtree_footer_args',
     'system_root_image',
     'root_dir',
     'ab_update',
@@ -193,7 +193,7 @@ SINGLE_BUILD_PARTITIONS = (
     'DATA/',
     'ODM/',
     'PRODUCT/',
-    'PRODUCT_SERVICES/',
+    'SYSTEM_EXT/',
     'RADIO/',
     'RECOVERY/',
     'ROOT/',