chore(issues): Reserve the rollback slug and rollback.sentry.io (#79764)

Confirmed this slug is also not currently reserved:
https://redash.getsentry.net/queries/7626/source

Author: mrduncan

src/sentry/constants.py

@@ -168,6 +168,7 @@ def get_all_languages() -> list[str]:
         "register",
         "remote",
         "resources",
+        "rollback",
         "sa1",
         "sales",
         "security",