Fix Juju kubernetes-master idle status never being set

[Cynerva]

What this PR does / why we need it:

This fixes a problem with the kubernetes-master charm where the "Kubernetes master running." status message never gets set.

This happens because the kube-api-endpoint.connected state that it's waiting for doesn't exist. The state we need is kube-api-endpoint.available as seen here.

Additionally, we need to add the relation arguments to idle_status so it doesn't break when called.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #47676

Special notes for your reviewer:

Release note:

Fix Juju kubernetes-master idle status never being set

[k8s-ci-robot]

Hi @Cynerva. Thanks for your PR.

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[lazypower]

/approve

[lazypower]

/assign @chuckbutler

[eparis]

@k8s-bot ok to test
/release-note-none
/approve

I'll let someone who knows juju do the lgtm Do we NEED this in 1.7? If so I think you need to open an issue.

[lazypower]

@eparis its a status message fix, low priority papercut.

[lazypower]

/lgtm

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Cynerva, chuckbutler, eparis

No associated issue. Update pull-request body to add a reference to an issue, or get approval with /approve no-issue

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Needs approval from an approver in each of these OWNERS Files:

• cluster/juju/OWNERS [chuckbutler,eparis]

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[Cynerva]

I went ahead and opened an issue and updated the PR to reference it.

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 47626, 47674, 47683, 47290, 47688)