Linter warnings for `_test.go` files

[michel-laterman]

Running golangci-lint run on this repo returns a lot of warnings related in our test files.

A majority of these warnings are related to:

• copying a variable within a loop i.e., tc := tc which is no longer needed (since go 1.22+)
• using context.Background() instead of t.Context() in tests (added in go 1.24).

We should fix these issues

[codeimmortal]

I can pick this.

[codeimmortal]

Raised PR for this #4875