Set the upper bound on FTS Probe GUCs to 3600 seconds

Using INT_MAX is problematic in the case of gp_fts_probe_timeout
since calculations on it can overflow at INT_MAX. Using INT_MAX
gp_fts_probe_interval won't overflow with current usage but running
the FTS probe every INT_MAX seconds is nonsensical.

src/backend/utils/misc/guc_gp.c

@@ -4117,7 +4117,7 @@ struct config_int ConfigureNamesInt_gp[] =
 			GUC_UNIT_S
 		},
 		&gp_fts_probe_timeout,
-		20, 0, INT_MAX, NULL, NULL
+		20, 0, 3600, NULL, NULL
 	},
 
 	{
@@ -4127,7 +4127,7 @@ struct config_int ConfigureNamesInt_gp[] =
 			GUC_UNIT_S
 		},
 		&gp_fts_probe_interval,
-		60, 10, INT_MAX, NULL, NULL
+		60, 10, 3600, NULL, NULL
 	},
 
 	{