Duplicate warnings about old absolute include mechanism congest logs
Description
https://mycore.atlassian.net/browse/MCR-2868 introduced a log message that is logged every time a stylesheet includes another stylesheet using the old absolute mechanism. In an established MyCoRe instance, for example ones based on the current MIR, this might generate al lot of messages every time a result page for an object is rendered (example output below). These messages are certainly helpful, but they are exactly the same for each render. Suppressing duplicate messages will keep the helpfulness and keep the log a bit cleaner/clearer.
https://mycore.atlassian.net/browse/MCR-2868 introduced a log message that is logged every time a stylesheet includes another stylesheet using the old absolute mechanism. In an established MyCoRe instance, for example ones based on the current MIR, this might generate al lot of messages every time a result page for an object is rendered (example output below). These messages are certainly helpful, but they are exactly the same for each render. Suppressing duplicate messages will keep the helpfulness and keep the log a bit cleaner/clearer.
Example: