out_azure_logs_ingestion: fix NULL dereference (#7624)

The code checks if `ctx` is NULL, and if it is' NULL proceeds to
dereference `ctx` by way of `ctx->ins`. As such, there will always be a
NULL dereference if the condition `if (!ctx)` is true. This fixes it by
removing the dereference.

plugins/out_azure_logs_ingestion/azure_logs_ingestion.c

@@ -43,7 +43,7 @@ static int cb_azure_logs_ingestion_init(struct flb_output_instance *ins,
     /* Allocate and initialize a context from configuration */
     ctx = flb_az_li_ctx_create(ins, config);
     if (!ctx) {
-        flb_plg_error(ctx->ins, "configuration failed");
+        flb_plg_error(ins, "configuration failed");
         return -1;
     }