fix(region_config): fix configure endpoint bug in getRegionPrefix

[windmgc]

Summary

This PR fixes a bug inside generateRegionPrefix that caused some service endpoint in specific region is not getting configured correctly.

lua-resty-aws/src/resty/aws/init.lua

Lines 138 to 149 in 50d9f08

	local function generateRegionPrefix(region)
	if not region then
	return nil, "no region given"
	end
	local parts = split(region, "-", true)
	if #parts < 3 then
	return nil, "not a valid region, only 2 parts; "..region
	end
	parts[#parts] = "*"
	return table.concat(parts, "-")
	end

This code originates from the JS code here:

function generateRegionPrefix(region) {
  if (!region) return null;
  var parts = region.split('-');
  if (parts.length < 3) return null;
  return parts.slice(0, parts.length - 2).join('-') + '-*';
}

There is a bug in our Lua code, that parts.slice(0, parts.length - 2).join('-') + '-*' is fetching the [0, #parts-2) items from the region parts and concatenating with another asterisk. But our SDK is just replacing the last item in the array with an asterisk, which equals fetching [0, #parts-2] and concatenating with another asterisk. (Here I'm using an index starting with 0 to clarify the difference). This caused different results when we generated region prefixes: a region cn-north-1 will result in cn-* in the JS function and cn-north-* in the Lua function.

The PR fixes it and lets the region_config_data apply correctly.

Issue

FTI-6159 mentioned an issue caused by this bug, which happens inside cn-north-1 that is expected to apply the cn-*/* endpoint config. The bug caused a mismatch and endpoint config cannot be applied correctly. This bug would also influence other regions like us-isob-east-1

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