Enable plugin to global_rules in 'Plugin List', dashboard will removed the _meta.filter setting when insert the plugin to ETCD.

[FionJHYang]

Issue description

Enable plugin to global_rules in 'Plugin List', dashboard will removed the _meta.filter setting when insert the plugin to ETCD.

if I want insert the request-validation plugin like below setting:
{ "_meta": { "disable": true, "filter": [ [ "host", "~=", "test.com.tw" ] ] }, "header_schema": { "properties": { "Origin": { "type": "string" } }, "required": [ "Origin" ], "type": "object" } }

After click submit button, the data in ETCD will remove filter section like below:
{ "_meta": { "disable": true }, "header_schema": { "properties": { "Origin": { "type": "string" } }, "required": [ "Origin" ], "type": "object" } }

Expected behavior

The data in ETCD should look like this:
{ "_meta": { "disable": true, "filter": [ [ "host", "~=", "test.com.tw" ] ] }, "header_schema": { "properties": { "Origin": { "type": "string" } }, "required": [ "Origin" ], "type": "object" } }

How to Reproduce

1. Login Apisix Dashboard
2. Click side menu 'Plugin'
3. Click 'Enable' button to enable a plugin
4. Select one plugin to enable and set _meta.filter config
5. Click submit to finish enable

Screenshots

No response

Environment

• apisix version (cmd: apisix version): 3.8.0
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run etcd --version): 3.5.10
• apisix-dashboard version, if have: 3.0.0
• Browser version, if have:

Additional context

No response