There is a number of critical log messages that we see in CI from time
to time. While these should be fixed, let's not fail jobs unnecessarily.

This change introduces one expected critical message in
placement-api.log:

    Failed to fetch token data from identity server

Co-authored-by: Radosław Piliszek <radoslaw.piliszek@gmail.com>
Related-bug: #1847727
Change-Id: I92ad0be70ed05925612f0c709907ab62280326b8

Also makes check-logs clear the aggregate files
to prevent duplicates due to upgrade and post.

Change-Id: I72377b6ac48e29dc5e24d1e3bd343e87b74a7a71

This script has a few issues:

* It catches false positives, due to log levels in config options.

* It doesn't fail on CRITICAL logs, due to variable reset issue.

This change fixes these.

Change-Id: I50c859eb2991e498eeb64bca45daf1e6f237761f

At the end of a CI run, check all log files.

Change-Id: I99afc1c5207757e35beabf7daebd86c56151c96d