update metadata file to add the 1.5 releases

[cpanato]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

• update metadata file to add the 1.5 releases
  this was missing for the 1.5 series

/assign @richardcase @dims

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

update metadata file to add the 1.5 releases

[cpanato]

/cherry-pick release-1.5

[k8s-infra-cherrypick-robot]

@cpanato: once the present PR merges, I will cherry-pick it on top of release-1.5 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.5

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.

[dims]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, dims

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:

• OWNERS [cpanato,dims]

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

[k8s-infra-cherrypick-robot]

@cpanato: new pull request created: #1057

In response to this:

/cherry-pick release-1.5

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.