Revert "Add soong config variable Release_expose_flagged_api"

Revert submission 2755310

Reason for revert: Broken build b/302407753

Reverted changes: /q/submissionid:2755310

Change-Id: If2b09e6609cdd4c47eea12cb2d877c3874e0560b
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 52bcd9a..e3eb780 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -40,9 +40,7 @@
 $(call add_json_str,  Platform_base_os,                  $(PLATFORM_BASE_OS))
 $(call add_json_str,  Platform_version_last_stable,      $(PLATFORM_VERSION_LAST_STABLE))
 $(call add_json_str,  Platform_version_known_codenames,  $(PLATFORM_VERSION_KNOWN_CODENAMES))
-
 $(call add_json_bool, Release_aidl_use_unfrozen,         $(RELEASE_AIDL_USE_UNFROZEN))
-$(call add_json_bool, Release_expose_flagged_api,        $(RELEASE_EXPOSE_FLAGGED_API))
 
 $(call add_json_str,  Platform_min_supported_target_sdk_version, $(PLATFORM_MIN_SUPPORTED_TARGET_SDK_VERSION))