Mount google-cloud-sdk into e2e image (#1997)

[sre-bot]

cherry-pick #1997 to release-1.1

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What problem does this PR solve?

fixes https://internal.pingcap.net/idc-jenkins/blue/organizations/jenkins/tidb-operator-e2e-gke-ci-master/detail/tidb-operator-e2e-gke-ci-master/62/pipeline

[2020-03-19T19:01:24.731Z] [5] E0319 19:01:24.307547      15 actions.go:907] failed to get tidbcluster: tidb-cluster-4946/basic-v2, Get https://104.155.180.0/apis/pingcap.com/v1alpha1/namespaces/tidb-cluster-4946/tidbclusters/basic-v2: error executing access token command "/google-cloud-sdk/bin/gcloud config config-helper --format=json": err=fork/exec /google-cloud-sdk/bin/gcloud: no such file or directory output= stderr=

e2e image needs to run /google-cloud-sdk/bin/gcloud config config-helper to refresh the auth token when it expired.

What is changed and how does it work?

Check List

Tests

• Unit test
• E2E test
• Stability test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has Go code change
• Has CI related scripts change
• Has Terraform scripts change

Side effects

• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Does this PR introduce a user-facing change?:

NONE