ovn-northd-ddlog: Fix memleak when destroying context.

This is benign but AddressSanitizer was complaining about it:

Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x7fa93cd6d667 in __interceptor_malloc (/lib64/libasan.so.6+0xb0667)
    #1 0x1be8d3e in xmalloc__ lib/util.c:137
    #2 0x1be8e1a in xmalloc lib/util.c:172
    #3 0x1b799d3 in json_create lib/json.c:1451
    #4 0x1b74314 in json_integer_create lib/json.c:263
    #5 0x1b7d38a in jsonrpc_create_id lib/jsonrpc.c:563
    #6 0x1b7d3a5 in jsonrpc_create_request lib/jsonrpc.c:570
    #7 0x1b8d851 in ovsdb_cs_send_transaction lib/ovsdb-cs.c:1376
    #8 0x40b017 in northd_send_output_only_data_request northd/ovn-northd-ddlog.c:290
    #9 0x40c802 in northd_run northd/ovn-northd-ddlog.c:568
    #10 0x410225 in main northd/ovn-northd-ddlog.c:1289
    #11 0x7fa93c4a9081 in __libc_start_main ../csu/libc-start.c:308

Signed-off-by: Dumitru Ceara <[email protected]>
Acked-by: Ben Pfaff <[email protected]>

northd/ovn-northd-ddlog.c

@@ -206,6 +206,7 @@ northd_ctx_destroy(struct northd_ctx *ctx)
 {
     if (ctx) {
         ovsdb_cs_destroy(ctx->cs);
+        json_destroy(ctx->request_id);
         json_destroy(ctx->output_only_data);
         free(ctx->prefix);
         free(ctx);