We generally follow the rule that for time settings we suffix the setting name
with "Sec" to indicate the default unit if none is specified. The only
exception was the rate limiting interval settings. Fix this, and keep the old
names for compatibility.
Do the same for journald's RateLimitInterval= setting
This is useful to prohibit execution of non-native processes on systems,
for example 32bit binaries on 64bit systems, this lowering the attack
service on incorrect syscall and ioctl 32→64bit mappings.
