Linter warnings for `_test.go` files

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