Change default Broker delivery spec

[pierDipi]

Problem

Our Broker delivery spec is unset by default, which means that it has literally a
fire-and-forget delivery guarantee because with don't retry.

To make our defaults stronger, we should set a reasonable delivery spec
by default when no delivery spec is specified.

Default Delivery Spec

The following delivery spec isn't perfect for every use case by at least
prevents events loss for normal networking errors (eg connection resets, etc)
or during upgrades.

delivery:
  retry: 10
  backoffPolicy: exponential
  backoffDelay: PT0.2S

The retry period with the above configuration is ~200 seconds long

Persona:
Which persona is this feature for?

• Event Consumer

Exit Criteria
A measurable (binary) test that would indicate that the problem has been resolved.

• Our delivery spec is set by default if not specified

Time Estimate (optional):
How many developer days do you think this may take to resolve?
1

Additional context (optional)

/area broker
/area delivery
/kind feature-request
/priority important-soon

Let me know what you think!

[knative-prow-robot]

@pierDipi: The label(s) area/broker cannot be applied, because the repository doesn't have them.

In response to this:

Problem

Our Broker delivery spec is unset by default, which means that it has literally a
fire-and-forget delivery guarantee because with don't retry.

To make our defaults stronger, we should set a reasonable delivery spec
by default when no delivery spec is specified.

Default Delivery Spec

The following delivery spec isn't perfect for every use case by at least
prevents events loss for normal networking errors (eg connection resets, etc)
or during upgrades.

delivery:
 retry: 10
 backoffPolicy: exponential
 backoffDelay: PT0.3S

The retry period with the above configuration is ~5min long
(ie the last retry is after about 5min)

Persona:
Which persona is this feature for?

• Event Consumer

Exit Criteria
A measurable (binary) test that would indicate that the problem has been resolved.

• Our delivery spec is set by default if not specified

Time Estimate (optional):
How many developer days do you think this may take to resolve?
1

Additional context (optional)

/area broker
/area delivery
/kind feature-request
/priority important-soon

Let me know what you think!

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