Remove use of `fmt.Sprintf` of with `slog`

[CDRayn]

Description

fmt.Sprintf() is used in combination with calls to the slog package. This is practice is discouraged when using slog. Instead non-static values to include in the log message should be passed to the logger as key value pairs. These uses of fmt.Sprint() and slog must be removed. pkg/rscache/file.go#280 for an instance of this improper usage.

[IrvingMg]

Hi, I'd like to take this issue.