change LOG_FORMAT to NU_LOG_FORMAT in nu-std library

[stormasm]

this closes #10248

@fdncred pointed out the problem and he was correct 😄

I went ahead and made the simple change and the
https://github.com/influxdata/influxdb_iox binary
works like a charm...

@amtoine hopefully there are no issues with this change

I believe its a good one as other rust binaries might take advantage of this common
environment variable as well...

[fdncred]

There was discussion a month back or so about using a consistent log format across nushell and std-lib. I wonder if that is why this was originally named LOG_FORMAT. Anyone remember?

[amtoine]

There was discussion a month back or so about using a consistent log format across nushell and std-lib. I wonder if that is why this was originally named LOG_FORMAT. Anyone remember?

i think i remember this but as i cannot remember what was said and as we did not go further with that idea, i think we should make the change in the problematic part of Nushell, i.e. the LOG_FORMAT from std and see later to integrate with main Nushell if we want 😋

[amtoine]

i see three LOG_FORMATs on main, this PR changes 3 of them, i think this is just perfect 👍

thanks @stormasm 🙏