The buildIdentityProfile() method is called only from
Authenticate.getOAuthCallback(), which has previously called
Authenticator.Authenticate(). It looks like all implementations of the
Authenticator interface already call UpdateUserInfo(), so we shouldn't
need to call UpdateUserInfo() a second time from buildIdentityProfile().
This should simplify the code a little and provide a slight performance
improvement (by avoiding one network request).
Currently the Authenticate.storeIdentityProfile() method always emits an
Error log. If there is no error from cookieChunker.SetCookie(), this
results in an empty log entry:
{"level":"error","time":"2023-06-27T23:56:38Z"}
Refactor this method to instead return the error from SetCookie(), and
update the calling code so that it logs a message only when this error
is non-nil.
(Moving the log call to the calling method gives access to the request
context, so the log entry will include the request ID and other related
info.)
