feat: is_authenticated request logging + cleanup

[jennifer-richards]

The main goal here is adding the is_authenticated field to gunicorn logs for the datatracker. This is done by adding an X-Datatracker-Is-Authenticated header to the response. This is used by the gunicorn logs, then stripped out by nginx.

On dev systems, this header will be reported. We could strip it out there as well, but it seems harmless to me.

Also does a little logging cleanup

• drops the X-Real-IP header and logging, which we're not using and is unlikely to be useful
• changes the log label duration_ms to duration_s and logs seconds, both for nginx and gunicorn. Before this, nginx was logging seconds with an incorrect label. Gunicorn was logging ms correctly, but for simplicity this keeps them in the same units. (Both are fractional, so either 1.234 or 1.234000, will show up in the logs)

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 6 lines in your changes missing coverage. Please review.

Project coverage is 88.77%. Comparing base (c7f6bde) to head (b1b8358).
Report is 56 commits behind head on main.

Files with missing lines	Patch %	Lines
ietf/middleware.py	66.66%	4 Missing ⚠️
ietf/utils/jsonlogger.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7893      +/-   ##
==========================================
- Coverage   88.78%   88.77%   -0.02%     
==========================================
  Files         296      304       +8     
  Lines       41320    41460     +140     
==========================================
+ Hits        36687    36807     +120     
- Misses       4633     4653      +20     

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