Add support for pg_stat_reset_slru without argument

pg_stat_reset_slru currently requires an input argument, either:
- NULL to reset the SLRU counters of everything.
- A specific value to reset a single SLRU cache.

This commit adds support for a new pattern: pg_stat_reset_slru without
any argument works the same way as pg_stat_reset_slru(NULL), relying on
a DEFAULT in the function definition to handle this case.  This makes
the function more consistent with 23c8c0c8f4.

Bump catalog version.

Author: Bharath Rupireddy
Reviewed-by: Atsushi Torikoshi
Discussion: https://postgr.es/m/CALj2ACW1VizYg01EeH_cA-7qA+4NzWVAoZ5Lw9_XYO1RRHAZbA@mail.gmail.com

src/backend/catalog/system_functions.sql

@@ -628,6 +628,13 @@ LANGUAGE INTERNAL
 CALLED ON NULL INPUT VOLATILE PARALLEL SAFE
 AS 'pg_stat_reset_shared';
 
+CREATE OR REPLACE FUNCTION
+  pg_stat_reset_slru(target text DEFAULT NULL)
+RETURNS void
+LANGUAGE INTERNAL
+CALLED ON NULL INPUT VOLATILE PARALLEL SAFE
+AS 'pg_stat_reset_slru';
+
 --
 -- The default permissions for functions mean that anyone can execute them.
 -- A number of functions shouldn't be executable by just anyone, but rather