bug: traffic-split plugin does not verify the UpstreamID is valid

[Nobilta]

Current Behavior

when i use traffic-split on a route,if i use a not exist upstream id,it will not verify this upstream id is valid.
{ "uri": "/index.html", "plugins": { "traffic-split": { "rules": [ { "weighted_upstreams": [ { "upstream_id": "abcdefg",//this upstreamid is not exist,but this request will success "weight": 1 }, { "weight": 1 } ] } ] } }, "upstream_id": "abcdefg",//this upstreamid is not exist,but this request will failed }

Expected Behavior

No response

Error Logs

No response

Steps to Reproduce

set traffic-split plugin on route,and set a not exist upstreamid

Environment

• APISIX version (run apisix version):3.3
• Operating system (run uname -a):
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):

[shreemaan-abhishek]

I could reproduce this, let me bring a fix.