Revert "get_cloudsync_context must be allocated in a global context"

This reverts commit 4e614f1.

Author: marcobambini

src/postgresql/cloudsync_postgresql.c

@@ -48,9 +48,7 @@ static cloudsync_context *pg_cloudsync_context = NULL;
 static cloudsync_context *get_cloudsync_context(void) {
     if (pg_cloudsync_context == NULL) {
         // Create context - db_t is not used in PostgreSQL mode
-        MemoryContext old = MemoryContextSwitchTo(TopMemoryContext);
         pg_cloudsync_context = cloudsync_context_create(NULL);
-        MemoryContextSwitchTo(old);
         if (!pg_cloudsync_context) {
             ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), errmsg("Not enough memory to create a database context")));
         }