temp revert "Migrate external consumers to namespaced MySQL include targets"

This reverts commit 6f164a0.

Author: mszabo-wikia

third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlConnection.cpp

@@ -7,9 +7,9 @@
  */
 
 #include <folly/Exception.h>
+#include <mysql_async.h>
 #include <memory>
 #include <string>
-#include "mysql/server/include/mysql_async.h" // @manual=//mysql/server/include:mysql_async_namespaced
 
 #include "squangle/base/ExceptionUtil.h"
 #include "squangle/mysql_client/ConnectionOptions.h"

third-party/squangle/src/squangle/mysql_client/mysql_protocol/MysqlConnection.h

@@ -9,7 +9,7 @@
 #pragma once
 
 #include <fmt/format.h>
-#include "mysql/server/include/mysql.h" // @manual=//mysql/server/include:mysql_namespaced
+#include <mysql.h>
 
 #include "squangle/base/Base.h"
 #include "squangle/base/ConnectionKey.h"