archival: Delete replaced segments during spillover GC

Previously, if the spillover was enable we weren running normal GC
during the housekeeping run. Normal housekeeping is responsible for
removing segments evicted due to retention (which is not happening if
spillover region is not empty). But it also removes replaced segments.
So essentially, we have to run both types of GC on every spillover
housekeeping run.

src/v/archival/ntp_archiver_service.cc

@@ -2159,6 +2159,7 @@ ss::future<> ntp_archiver::housekeeping() {
             } else {
                 co_await apply_archive_retention();
                 co_await garbage_collect_archive();
+                co_await garbage_collect();
             }
             co_await apply_spillover();
         }