Issue description

According to the plugin's documentation: https://apisix.apache.org/docs/apisix/plugins/traffic-split/
I configured two rules:

"traffic-split": {
      "rules": [
        {
          "match": [
            {
              "vars": [
                [
                  "http_x-my-header",
                  "==",
                  "1"
                ]
              ]
            }
          ],
          "weighted_upstreams": [
            {
              "upstream_id": "demo-1",
              "weight": 100
            }
          ]
        },
        {
          "weighted_upstreams": [
            {
              "upstream_id": "demo-2",
              "weight": 50
            },
            {
              "weight": 50
            }
          ]
        }
      ]
    }

When the first rule does not match, the second rule also fails, I looked at the relevant code, the problem should be here:

Environment

• apisix version (cmd: apisix version): 2.12.0

Steps to reproduce

1、create arbitrary routes
2、add traffic-split plugin for it config like above
3、access the relevant route, intentionally not matching the first rule

Actual result

The second rule is ignored

Error log

2022/02/10 19:46:47 [info] 137#137: *898767 [lua] traffic-split.lua:264: phase_func(): match_passed: false, client: 127.0.0.1, server: _, request: "GET /demo/ip HTTP/1.1", host: "test.com"

Expected result

The second rule should be matched