Revert "Show index search count in EXPLAIN ANALYZE."

This reverts commit 5ead85fbc8.

This commit shows test failures with debug_parallel_query=regress.  The
underlying issue needs to be debugged, so revert for now.

doc/src/sgml/ref/explain.sgml

@@ -506,11 +506,10 @@ EXPLAIN ANALYZE EXECUTE query(100, 200);
    Buffers: shared hit=4
    ->  Index Scan using test_pkey on test  (cost=0.29..10.27 rows=99 width=8) (actual time=0.009..0.025 rows=99.00 loops=1)
          Index Cond: ((id > 100) AND (id < 200))
-         Index Searches: 1
          Buffers: shared hit=4
  Planning Time: 0.244 ms
  Execution Time: 0.073 ms
-(10 rows)
+(9 rows)
 </programlisting>
   </para>