refactor(statsd): refactor workspace id and name retrieval

[sabertobihwy]

Summary

ws.get_workspace() function will execute database query, calling this function in the plugin for every request will lead to performance degradation.

Checklist

• The Pull Request has tests
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

• add a new function ws.get_workspace_name() that directly returns the default workspace name (default).

Issue reference

Fix FTI-5303

[hanshuebner]

Does this affect the use of the plugin with non-default workspaces? Please add a test that verifies that the plugin still works correctly with default and non-default workspaces.

[hanshuebner]

Please add the get_workspace_name function to EE first, referencing this PR. Also add a changelog file and a test.

[AndyZhang0707]

@sabertobihwy pls check the comments above.

[sabertobihwy]

Hi @hanshuebner, I submitted a corresponding PR to EE: https://github.com/Kong/kong-ee/pull/6375

NOTE: https://github.com/Kong/kong-ee/pull/6375 will not be merged. After this PR is merged(#11442), when cherry picking this PR to EE, it will be modified according to https://github.com/Kong/kong-ee/pull/6375, so https://github.com/Kong/kong-ee/pull/6375 is only used to demonstrate the ideas and details.

[sabertobihwy]

This PR is simple, an existing test case can be considered as already covered:

kong/spec/03-plugins/06-statsd/01-log_spec.lua

Lines 1491 to 1507 in d4d547d

	it("status_count_per_workspace", function()
	local metrics_count = expected_metrics_count(1)
	local thread = helpers.udp_server(UDP_PORT, metrics_count, 2)
	local response = assert(proxy_client:send {
	method = "GET",
	path = "/request?apikey=kong",
	headers = {
	host = "logging17.com"
	}
	})
	assert.res_status(200, response)
	local ok, res, err = thread:join()
	assert(ok, res)
	assert(res, err)
	assert.contains("kong.service.statsd17.workspace." ..
	workspace_name_pattern .. ".status.200:1|c", res, true)

[hanshuebner]

Please fix the PR description.

[kikito]

@vm-001 are your changes addressed on this PR?

[vm-001]

@vm-001 are your changes addressed on this PR?

Yes. So, approved.

[kikito]

@sabertobihwy please cherry-pick the change into kong-ee