fn: New timeout for LB Placer (#1137)

* fn: New timeout for LB Placer

Previously, LB Placers worked hard as long as
client contexts allowed for. Adding a Placer
config setting to bound this by 360 seconds by
default.

The new timeout is not accounted during actual
function execution and only applies to the amount
of wait time in Placers when the call is not
being executed.

api/server/server.go

@@ -586,12 +586,13 @@ func WithAgentFromEnv() Option {
 			}
 
 			// Select the placement algorithm
+			placerCfg := pool.NewPlacerConfig()
 			var placer pool.Placer
 			switch getEnv(EnvLBPlacementAlg, "") {
 			case "ch":
-				placer = pool.NewCHPlacer()
+				placer = pool.NewCHPlacer(&placerCfg)
 			default:
-				placer = pool.NewNaivePlacer()
+				placer = pool.NewNaivePlacer(&placerCfg)
 			}
 
 			keys := []string{"fn_appname", "fn_path"}