feat(plugins): allow creating dup plugins [khcp-10683] (#1153)

Remove the logic that prevents users from adding duplicate plugins of the same type to the same entity. We need to support creating multiple plugins of the same type for `consumers`/`consumer_groups` to allow scoping to multiple entities simultaneously (ie. I can create a plugin scoped to a specific `consumer_group`/`route` and have a different configuration for the same plugin when it's scoped to a specific `consumer_group`/`gateway-service` correctly).
Addresses [KHCP-10683](https://konghq.atlassian.net/browse/KHCP-10683).

Author: kaiarrowood

packages/entities/entities-plugins/src/components/PluginSelect.vue

@@ -344,14 +344,6 @@ const buildPluginList = (): PluginCardList => {
         plugin.disabledMessage = props.disabledPlugins[pluginId]
       }
 
-      if (existingEntityPlugins.value.includes(pluginId)) {
-        plugin.exists = true
-
-        if (!plugin.disabledMessage) {
-          plugin.disabledMessage = t('plugins.select.already_exists')
-        }
-      }
-
       const groupName = plugin.group || t('plugins.select.misc_plugins')
       let plugins = list[groupName]