Cherry-pick #607, #627 and #841 to branch release-0.7

[lzhecheng]

What type of PR is this?

What this PR does / why we need it:

Cherry-pick #607, #627 and #841 to branch release-0.7 to solve flaky tests.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Cherry-pick #607 to solve flaky tests:
* should add all nodes in different agent pools to backends [MultipleAgentPools]: fail to find `backendAddressPoolID` in `lbBackendAddressPoolsIDMap`
* Found no or more than 1 virtual network in resource group same as cluster name
* cannot obtain the master node

Failures e.g.
https://prow.k8s.io/view/gs/kubernetes-jenkins/pr-logs/pull/kubernetes-sigs_cloud-provider-azure/969/pull-cloud-provider-azure-e2e-ccm-capz-1-20/1479028839588827136

Cherry-pick #627 to solve "get outbound rules" issue
Cherry-pick #841 to solve "not equal 0" issue

Failures e.g.
https://prow.k8s.io/view/gs/kubernetes-jenkins/pr-logs/pull/kubernetes-sigs_cloud-provider-azure/982/pull-cloud-provider-azure-e2e-ccm-capz-1-20/1480370475220602880

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Hi @lzhecheng. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[lzhecheng]

@nilo19 please help ok-to-test

[nilo19]

/ok-to-test

[feiskyer]

Could you add a release note in the PR description part (inside release note part):

```release-note

[lzhecheng]

This time only 2 tests in pull-cloud-provider-azure-e2e-ccm-capz-1-20 failed:

• should make outbound IP of pod same as in SLB's outbound rules: outbound rule number should not equal 0
• should support updating internal IP when updating internal service: WaitServiceExposure() timeout

Added 2 fix commits and trigger the test again.

[nilo19]

/lgtm
/approved

[nilo19]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lzhecheng, nilo19

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• OWNERS [nilo19]

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[nilo19]

/kind flake