refactor: remove use_xml_format (#1535)

lua/avante/providers/bedrock.lua

@@ -5,7 +5,6 @@ local P = require("avante.providers")
 local M = {}
 
 M.api_key_name = "BEDROCK_KEYS"
-M.use_xml_format = true
 
 M = setmetatable(M, {
   __index = function(_, k)

lua/avante/providers/claude.lua

@@ -29,7 +29,6 @@ end
 local M = {}
 
 M.api_key_name = "ANTHROPIC_API_KEY"
-M.use_xml_format = true
 M.support_prompt_caching = true
 
 M.role_map = {

lua/avante/providers/init.lua

@@ -224,8 +224,6 @@ M = setmetatable(M, {
     -- default to gpt-4o as tokenizer
     if t[k].tokenizer_id == nil then t[k].tokenizer_id = "gpt-4o" end
 
-    if t[k].use_xml_format == nil then t[k].use_xml_format = true end
-
     if t[k].is_env_set == nil then t[k].is_env_set = function() return E.parse_envvar(t[k]) ~= nil end end
 
     if t[k].setup == nil then