renepay: small tweak to decay time

The time of decay "TIMER_FORGET_SEC" was set to 1 hour,
which is very low, it would make the plugin try depleted channels after
just a couple of seconds for very small amounts.
I set it to 1 week ~ 6e5 seconds.

Signed-off-by: Lagrang3 <[email protected]>

Author: Lagrang3

plugins/renepay/renepayconfig.h

@@ -6,7 +6,7 @@
 
 /* Knowledge is proportionally decreased with time up to TIMER_FORGET_SEC when
  * we forget everything. */
-#define TIMER_FORGET_SEC 3600
+#define TIMER_FORGET_SEC 600000
 
 /* Time lapse used to wait for failed sendpays. */
 #define COLLECTOR_TIME_WINDOW_MSEC 50