Reduce the amount of timings that are printed with -v{2, ...} and -ddump-timings

We instead leave the choice to callers of withTiming, and make sure not to print timings when withTiming is repeatedly called around small computations. This is achieved by adding an extra argument where the caller specifies whether timings should be printed (when using -v<N> with N >= 2 or -ddump-timings).

This addresses #17138 (closed).