psql: Make test robust against locale variations

The test committed in 1a759c8327 was prone to failing when using
locales with a different decimal separator.  Since the test value
isn't the important part, change to using an integer instead.

Author: Daniel Gustafsson <daniel@yesql.se>
Reported-by: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://postgr.es/m/CAFj8pRDE=7uW7QP4rg-OQLE2i-puYsUUt+eHE-L6_b_J9w=eWg@mail.gmail.com

src/bin/psql/t/001_basic.pl

@@ -436,12 +436,12 @@ psql_fails_like(
 psql_like(
 	$node,
 	'\echo :WATCH_INTERVAL
-\set WATCH_INTERVAL 0.001
+\set WATCH_INTERVAL 10
 \echo :WATCH_INTERVAL
 \unset WATCH_INTERVAL
 \echo :WATCH_INTERVAL',
 	qr/^2$
-^0.001$
+^10$
 ^2$/m,
 	'WATCH_INTERVAL variable is set and updated');
 psql_fails_like(