perfschema.relaylog can fail based on the path of the build directory

The MTR test perfschema.relaylog has many substring operations where it looks for files with wildcards, e.g. "%master-%", in the table performance_schema.file_summary_by_instance. However, if any folder names in the path of the server are matched, the test will fail because all records will be matched and output.

Easy to reproduce by renaming your mariadb git working directory to "master-test" or by cloning the repo with that name, e.g.

git clone git@github.com:MariaDB/server.git master-test

and building the source code and running the test perfschema.relaylog as normal.