test_df::test_total fails on linux arm64

[sylvestre]

See:
#7153

---- test_df::test_total stdout ----
run: /home/runner/work/coreutils/coreutils/target/aarch64-unknown-linux-gnu/debug/coreutils df --total
thread 'test_df::test_total' panicked at tests/by-util/test_df.rs:399:5:
assertion `left == right` failed
  left: 66261398
 right: 66261397
stack backtrace:
   0: rust_begin_unwind
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:652:5
   1: core::panicking::panic_fmt
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:72:14
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:364:5
   4: tests::test_df::test_total
             at ./tests/by-util/test_df.rs:399:5
   5: tests::test_df::test_total::{{closure}}
             at ./tests/by-util/test_df.rs:361:16
   6: core::ops::function::FnOnce::call_once
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:250:5
   7: core::ops::function::FnOnce::call_once
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.