test: remove unnecessary response body data check

[Chever-John]

What this PR does / why we need it:

In the test file, there is a lot of redundant request response body data, and some just duplicate the input content. For this reason, a PR is needed to improve the test example situation.

Fix #6538

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[spacewander]

Look like we need to update:

ngx.status = code

to

if code >= 300 then
    ngx.status = code
end

Because the response data check will convert the status code to 200:

apisix/t/lib/test_admin.lua

Lines 204 to 214 in 9b0460f

	if pattern == nil then
	return res.status, "passed", res.body, res.headers
	end
	local res_data = json.decode(res.body)
	local ok, err = _M.comp_tab(pattern, res_data)
	if not ok then
	return 500, "failed, " .. err, res_data
	end
	return 200, "passed", res_data, res.headers