[libFuzzer] Use uppercase "B" for byte units in output (#220828)

Fixes issue #56766. libFuzzer printed data sizes as "b", "Kb" and "Mb",
which denote bits. Use "B", "KB" and "MB" instead.

GitOrigin-RevId: 20ddf3e2f5a9fa2717d9cfea19660ef1f0399044
3 files changed