Remove duplicated percentage signs in sprintf.js

What does this MR do and why?

It updates sprintf function so it ignore the extra percentage sign.

Example: %%{someVariable}%% would be handled as %{someVariable}%%

The original discussion is linked in the issue.

Screenshots or screen recordings

N/A

How to set up and validate locally

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #362541 (closed)