test/dd: fix broken pipe in test_bytes_oseek_bytes_trunc_oflag

[niyaznigmatullin]

Fixes #3581

I think that happens because count=0 is stated, dd won't read anything from stdin. So the process could finish before we wrote something to stdin pipe, and broken pipe error is raised.

• Add ignore_stdin_write_error for this test

[sylvestre]

The mac test failures are unrelated:

---- test_uptime::test_uptime stdout ----
current_directory_resolved: 
run: /Users/runner/work/coreutils/coreutils/target/debug/coreutils uptime
---- test_uptime::test_uptime stderr ----
thread 'main' panicked at 'Command was expected to succeed.
stdout = 
 stderr = uptime: could not retrieve system uptime
', tests/common/util.rs:176:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- test_uptime::test_uptime_since stdout ----
current_directory_resolved: 
run: /Users/runner/work/coreutils/coreutils/target/debug/coreutils uptime --since
---- test_uptime::test_uptime_since stderr ----
thread 'main' panicked at 'Command was expected to succeed.
stdout = 
 stderr = uptime: could not retrieve system uptime
', tests/common/util.rs:176:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace