Update Slack URL

[craigbox]

A new URL generated by Slack support will last us for 1 year or 2000 uses, whatever comes first.

/cc @kfaseela @hzxuzhonghu @howardjohn

[istio-policy-bot]

😊 Welcome @craigbox! This is either your first contribution to the Istio test-infra repo, or it's been
awhile since you've been here.

You can learn more about the Istio working groups, code of conduct, and contributing guidelines
by referring to Contributing to Istio.

Thanks for contributing!

Courtesy of your friendly welcome wagon.

[howardjohn]

Terraform will perform the following actions:

  # google_cloud_run_v2_service.redirector will be updated in-place
  ~ resource "google_cloud_run_v2_service" "redirector" {
        id                      = "projects/istio-io/locations/us-central1/services/redirector"
        name                    = "redirector"
        # (17 unchanged attributes hidden)

      ~ template {
            # (6 unchanged attributes hidden)

          ~ containers {
                # (3 unchanged attributes hidden)

              ~ env {
                    name  = "REDIRECT_URL"
                  ~ value = "https://join.slack.com/t/istio/shared_invite/zt-22l940p1h-HdIPYKoZy8JzOAqTCfuOnA" -> "https://join.slack.com/t/istio/shared_invite/zt-23hxe505s-dqKi3O~~YzYA88Qw1ITzeA"
                }

                # (3 unchanged blocks hidden)
            }

            # (1 unchanged block hidden)
        }

        # (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

google_cloud_run_v2_service.redirector: Modifying... [id=projects/istio-io/locations/us-central1/services/redirector]
google_cloud_run_v2_service.redirector: Still modifying... [id=projects/istio-io/locations/us-central1/services/redirector, 10s elapsed]
google_cloud_run_v2_service.redirector: Still modifying... [id=projects/istio-io/locations/us-central1/services/redirector, 20s elapsed]
google_cloud_run_v2_service.redirector: Still modifying... [id=projects/istio-io/locations/us-central1/services/redirector, 30s elapsed]
google_cloud_run_v2_service.redirector: Still modifying... [id=projects/istio-io/locations/us-central1/services/redirector, 40s elapsed]
google_cloud_run_v2_service.redirector: Modifications complete after 43s [id=projects/istio-io/locations/us-central1/services/redirector]

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.