chore: Remove unnecessary require statements

[moutten]

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• N/A [ ] I have added tests that prove my fix is effective or that my feature works
• N/A [ ] I have added necessary documentation about the functionality in the appropriate .md file
• N/A [ ] I have added in line documentation to the code I modified

Short description of what this PR does:

Because none of these files use the JSON library, it's not necessary
to use require 'json' at the beginning of the files. This is only a
minor cleanup but using more require statements does have the
potential to slow down applications when more gems are installed and
the include path grows within Ruby.

[SendGridDX]

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