Additional commands for prometheus and grafana

[akremsa]

What type of PR is this?

/kind cleanup

What this PR does / Why we need it:
While I was working on prometheus\grafana-related tasks I found that it would be nice to add some new commands inside a Makefile.

[agones-bot]

Build Succeeded 👏

Build Id: a0e907ab-4054-47e5-a18a-f14be3687b9e

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:1.7.0-9100471
• image: gcr.io/agones-images/agones-sdk:1.7.0-9100471
• image: gcr.io/agones-images/agones-ping:1.7.0-9100471
• Linux C++ SDK (build): agonessdk-1.7.0-9100471-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.7.0-9100471.zip

A preview of the website (the last 30 builds are retained):

• https://9100471-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1601/head:pr_1601 && git checkout pr_1601
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.7.0-9100471

[agones-bot]

Build Failed 😱

Build Id: 7a4631e7-8b72-495f-aecc-240a0eac4eb2

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[aLekSer]

Some E2E tests are failing due to change in consul lock name in #1611 . Previously it was LockE2E, now we need to have separate two locks, one per each E2E test cluster name.

[aLekSer]

These two commands would be useful.

[google-oss-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: akremsa, aLekSer
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[agones-bot]

Build Succeeded 👏

Build Id: 8e19a889-dc36-4012-8aeb-203fb80bd2e4

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:1.7.0-470ccaa
• image: gcr.io/agones-images/agones-sdk:1.7.0-470ccaa
• image: gcr.io/agones-images/agones-ping:1.7.0-470ccaa
• Linux C++ SDK (build): agonessdk-1.7.0-470ccaa-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.7.0-470ccaa.zip

A preview of the website (the last 30 builds are retained):

• https://470ccaa-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/GoogleCloudPlatform/agones.git pull/1601/head:pr_1601 && git checkout pr_1601
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.7.0-470ccaa