pgsql: Add support for pg_stat_reset_slru without argument

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 23c8c0c8f472.

Bump catalog version.

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

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e5cca6288a4098cf731599b5977b0f6714ba0ac6

Modified Files
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doc/src/sgml/monitoring.sgml             | 7 ++++---
src/backend/catalog/system_functions.sql | 7 +++++++
src/include/catalog/catversion.h         | 2 +-
src/include/catalog/pg_proc.dat          | 3 ++-
src/test/regress/expected/stats.out      | 2 +-
src/test/regress/sql/stats.sql           | 2 +-
6 files changed, 16 insertions(+), 7 deletions(-)