A bit of code refactoring

[EloyTolosaDev]

It started because I wanted to investigate on issue #785 , and I ended up refactoring the codebase a bit while working on it. In the end, I did nothing about the issue because I couldn't figure out what was happening, and I did not get any response from the person who created the issue, so I could not investigate further. After all, it looks like a user problem, as I was unable to reproduce the problem.

What changed?

Functionality did not change, the main changes were:

1. Removing an unused function "IsOutdatedConfig" as it was only checking if the length of the variable ProfileRegistryURLs and that could be done separately without any function.
2. Removed an unused error variable "RegistrySyncError" as it did not provide any extra functionality in the case of the error ocurred, also it was not being used.
3. Removed the awsmerge.Merger struct, and replacing the merger struct functions as package functions, as there were no differences and having an extra awsmerge.Merger struct which did nothing at all looked strange to me.

Why?

How did you test it?

I tested the dassume and dgranted binaries and worked as espected.

Potential risks

Is patch release candidate?

Link to relevant docs PRs