Avoid relying on message format in access logger test

This is already tested in access_log_record_test [#63074062]

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>
Handle absence of fields that might be missing in panic

Precursor to deferring the function that logs access [#63074062]

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>