only run gateway conformance tests during nightly builds

[dprotaso]

No description provided.

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dprotaso

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• test/OWNERS [dprotaso]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[izabelacg]

/lgtm

[dprotaso]

/override "Generate some code!"
/override "style / suggester / yaml"
/override "style / suggester / github_actions"
/override "style / Golang"

[knative-prow]

@dprotaso: Overrode contexts on behalf of dprotaso: Generate some code!, style / Golang, style / suggester / github_actions, style / suggester / yaml

In response to this:

/override "Generate some code!"
/override "style / suggester / yaml"
/override "style / suggester / github_actions"
/override "style / Golang"

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.