Fix some Rails 7 deprecations for `Time#to_s(format)`

What does this MR do and why?

As mentioned in https://github.com/rails/rails/pull/43772 and https://github.com/rails/rails/pull/43772, Rails 7 has deprecated Time#to_s(format) in favor of Time#to_fs(format)`. This commit updates a subset of the files with this change and eliminates some deprecation warnings.

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