set a default so that eds warms up by default

[kdorosh]

Gloo Endpoints warming timeout currently reads as:

	// Timeout to get initial snapshot of resources. If not set, Gloo will not wait for initial
	// snapshot - if set and and gloo could not fetch it's initial snapshot before the timeout
	// reached, gloo will panic.

We should change this to have a default of one minute. If set to 0s, then Gloo will not wait for the initial snapshot, as the previous default defines.

This will help reduce any potential downtime in upgrades with the default settings because Gloo will wait for EDS to sync before configuring Envoy.