A regular expression whose matches are removed from every tile label. Job names in a real Jenkins tend to share long prefixes and suffixes that carry no information on a wall; stripping them leaves more room for the part that differs, and lets the text be drawn larger. For example ^ci-|-pipeline$ turns ci-decision-control-pipeline into decision-control. Leftover separators are tidied up, and a pattern that would erase a name entirely is ignored for that job.