Replace base::RandInt with std::uniform_int_distribution

As part of the effort to uprev libchrome in Android, we are
removing Android dependencies to libchrome utility functions
that are not strictly required.
This CL remove the usage of base::RandInt and replace by std cpp

Bug: 360917504
Change-Id: I83ea0f00ca07074f8c6c9a69db343a65cc8deb27
Test: atest libfs_avb_internal_test