feat(ollama): do not inherit default models from OpenAI provider

With Ollama majority of people are using their own models, and Ollama
provider by default queries the server for list of models, so there is
no need to inherit anything.

lua/avante/providers/ollama.lua

@@ -8,7 +8,13 @@ local Prompts = require("avante.utils.prompts")
 ---@class AvanteProviderFunctor
 local M = {}
 
-setmetatable(M, { __index = Providers.openai })
+setmetatable(M, {
+  __index = function(_, k)
+    -- Filter out OpenAI's default models because everyone uses their own ones with Ollama
+    if k == "model" or k == "model_names" then return nil end
+    return Providers.openai[k]
+  end,
+})
 
 M.api_key_name = "" -- Ollama typically doesn't require API keys for local use