SEBSP-218 evict cache on session close

Author: anhefti

src/main/java/ch/ethz/seb/sps/server/servicelayer/impl/SessionServiceImpl.java

@@ -150,6 +150,7 @@ public void closeSession(final String sessionUUID) {
                             final String groupUUID = this.groupDAO.byPK(session.groupId).getOrThrow().uuid;
                             this.proctoringCacheService.evictSession(sessionUUID);
                             this.proctoringCacheService.evictSessionTokens(groupUUID);
+                            this.proctoringCacheService.evictSessionScreenshotData(sessionUUID);
                         } else {
                             result.getOrThrow();
                         }