Rename data/staging to data/pkg_staging.

Test: Build and flash, atest apex_e2e_tests
Fixes: 122999313
Change-Id: I2cfa49d8467d67edc470b1cade3746426fa86e37
diff --git a/private/file_contexts b/private/file_contexts
index 7797930..b79880b 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -452,7 +452,7 @@
 /data/preloads/media(/.*)?	u:object_r:preloads_media_file:s0
 /data/preloads/demo(/.*)?	u:object_r:preloads_media_file:s0
 /data/server_configurable_flags(/.*)? u:object_r:server_configurable_flags_data_file:s0
-/data/staging(/.*)?		u:object_r:staging_data_file:s0
+/data/pkg_staging(/.*)?		u:object_r:staging_data_file:s0
 
 # Misc data
 /data/misc/adb(/.*)?            u:object_r:adb_keys_file:s0