feat: use checker.name to format periodic lock to distribute active check task to multiple workers

[nic-6443]

Currently, using a constant as self.PERIODIC_LOCK causes all active health tasks to be processed by only one worker. Even if other workers receive a request associated with another checker, they cannot start the health check actually. ref:

lua-resty-healthcheck/lib/resty/healthcheck.lua

Lines 1214 to 1235 in 09a672e

	local function get_periodic_lock(shm, key)
	local my_pid = ngx_worker_pid()
	local checker_pid = shm:get(key)
	if checker_pid == nil then
	-- no worker is checking, try to acquire the lock
	local ok, err = shm:add(key, my_pid, LOCK_PERIOD)
	if not ok then
	if err == "exists" then
	-- another worker got the lock before
	return false
	end
	ngx_log(ERR, "failed to add key '", key, "': ", err)
	return nil, err
	end
	elseif checker_pid ~= my_pid then
	-- another worker is checking
	return false
	end
	return true
	end

lua-resty-healthcheck/lib/resty/healthcheck.lua

Lines 1726 to 1741 in 09a672e

	local shm, key = self.shm, self.PERIODIC_LOCK
	last_cleanup_check = ngx_now()
	active_check_timer, err = resty_timer({
	recurring = true,
	interval = CHECK_INTERVAL,
	jitter = CHECK_JITTER,
	detached = false,
	expire = function()
	if get_periodic_lock(shm, key) then
	active_check_timer.interval = CHECK_INTERVAL
	renew_periodic_lock(shm, key)
	else
	active_check_timer.interval = CHECK_INTERVAL * 10
	return
	end

lua-resty-healthcheck/lib/resty/healthcheck.lua

Line 1671 in 09a672e

self.PERIODIC_LOCK = SHM_PREFIX .. ":period_lock:"