web: remove duplicate log of errors (#6157)
web: remove duplicate log of errors (#6157)

The WFE logs internal errors as part of its request logging. These
errors are mostly passed along from other components, particularly the
SA, and spike whenever the database struggles with availability.

Since these are logged at error level, they mask other, potentially more
useful error logs. Remove these error logs in preference for the
info-level request logs, plus metrics that indicate when we are serving
a large proportion of 500s.
letsencrypt/boulder,letsencrypt/boulder,letsencrypt/boulder