Revert "Mark libmetricslogger vendor_available."

This reverts commit 7f96d49370.

Reason for revert: depends on private liblog APIs
- log/log_event_list.h is not in the vndk

Change-Id: I448c2f1059bd6b225d8efff87eb3948e931de47a

libmetricslogger/Android.bp

@@ -31,7 +31,6 @@ cc_defaults {
 // -----------------------------------------------------------------------------
 cc_library_shared {
     name: "libmetricslogger",
-    vendor_available: true,
     srcs: metricslogger_lib_src_files,
     defaults: ["metricslogger_defaults"],
 }