Allow regex for slot/platform in periodic test definition

Currently slot, platform and project accept wildcards that are matched using fnmatch.fnmatch. This does not allow for one of the primary use cases that is OR-ing different values (e.g. lhcb-master|lhcb-head).

This MR allows selecting slot and platform with a regex. To keep backward compatibility for the already used wildcards in test_scheduler2.xml, the fnmatch check is kept as well for platform.

This MR also removes the wildcard matching for project, where there are no uses of it and it is hard to imagine any (as the options will be project-specific anyway).