fix: run init_worker of apisix.admin module in stream subsystem

[nic-6443]

Description

In order for the admin API standalone mode to work properly in the stream subsystem, we need to execute the apisix.admin module initialization function like in the HTTP subsystem:

apisix/apisix/admin/standalone.lua

Lines 415 to 455 in 5e804cf

	function _M.init_worker()
	local function update_config(config)
	if not config then
	local err
	config, err = get_config()
	if not config then
	core.log.error("failed to get config: ", err)
	return
	end
	end
	-- remove metadata key in-place
	-- this table is generated by json decode, so there is no need to clone it
	config[METADATA_LAST_MODIFIED] = nil
	config[METADATA_DIGEST] = nil
	config_yaml._update_config(config)
	end
	events:register(update_config, EVENT_UPDATE, EVENT_UPDATE)
	-- due to the event module can not broadcast events between http and stream subsystems,
	-- we need to poll the shared dict to keep the config in sync
	local last_modified_per_worker
	timer_every(1, function ()
	if not exiting() then
	local config, err = get_config()
	if not config then
	if err ~= NOT_FOUND_ERR then
	core.log.error("failed to get config: ", err)
	end
	else
	local last_modified = config[METADATA_LAST_MODIFIED]
	if last_modified_per_worker ~= last_modified then
	update_config(config)
	last_modified_per_worker = last_modified
	end
	end
	end
	end)
	patch_schema()
	end

. The previous test cases called /apisix/admin/configs API in a prior test case and then test-nginx performed a reload, which led to executing the following code and failed to detect that the backend timer was not started correctly.

apisix/apisix/core/config_yaml.lua

Lines 395 to 429 in 5e804cf

	if is_use_admin_api() and not shared_dict then
	log.info("try to load config from shared dict")
	local config, err
	shared_dict = ngx_shared["standalone-config"] -- init shared dict in current worker
	if not shared_dict then
	log.error("failed to read config from shared dict: shared dict not found")
	goto SKIP_SHARED_DICT
	end
	config, err = shared_dict:get("config")
	if not config then
	if err then -- if the key does not exist, the return values are both nil
	log.error("failed to read config from shared dict: ", err)
	end
	log.info("no config found in shared dict")
	goto SKIP_SHARED_DICT
	end
	log.info("startup config loaded from shared dict: ", config)
	config, err = json.decode(tostring(config))
	if not config then
	log.error("failed to decode config from shared dict: ", err)
	goto SKIP_SHARED_DICT
	end
	_M._update_config(config)
	log.info("config loaded from shared dict")
	::SKIP_SHARED_DICT::
	if not shared_dict then
	log.crit(_M.ERR_NO_SHARED_DICT)
	-- fill that value to make the worker not try to read from shared dict again
	shared_dict = "error"
	end
	end

Which issue(s) this PR fixes:

Fixes #

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (If not, please discuss on the APISIX mailing list first)