fixup! survey: show some commits/trees/blobs histograms

The `OI_DBCACHED` flag was removed in 7a4bd1b (packfile: always
declare object info to be OI_PACKED, 2026-01-12). The commit message
suggests to use the `is_delta` flag instead, but that is only
populated if `OBJECT_INFO_QUICK` isn't passed (which is part of
`OBJECT_INFO_FOR_PREFETCH`, which we use here).

At the same time, no caller ever looked at the `cnt_dbcached` count. So
let's just remove it.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

builtin/survey.c

@@ -292,7 +292,6 @@ struct survey_stats_base_object {
 	uint32_t cnt_cached;   /* see oi.whence */
 	uint32_t cnt_loose;    /* see oi.whence */
 	uint32_t cnt_packed;   /* see oi.whence */
-	uint32_t cnt_dbcached; /* see oi.whence */
 
 	uint64_t sum_size; /* sum(object_size) */
 	uint64_t sum_disk_size; /* sum(disk_size) */
@@ -1416,9 +1415,6 @@ static void increment_totals(struct survey_context *ctx,
 		case OI_PACKED:
 			base->cnt_packed++;
 			break;
-		case OI_DBCACHED:
-			base->cnt_dbcached++;
-			break;
 		default:
 			break;
 		}