Automatic merge from submit-queue (batch tested with PRs 61829, 61908, 61307, 61872, 60100). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Use curl instead of wget to fetch the CNI tarball in e2e-node test

**What this PR does / why we need it**:

Curl is more ubiquitous than wget. For instance, the GCE centos-7 and rhel-7 image families ship curl by default, but not wget.

Looking at the shell scripts under cluster/, they tend to use curl more than wget. (The ones that use wget, such as get-kube.sh, try curl first and only fallback to wget if it's not available.)

**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 running node e2e test on centos-7 or rhel-7 image families provided in GCE.

**Special notes for your reviewer**:

Tested by running node-e2e-test on Ubuntu, COS and CentOS.

**Release note**:

```release-note
NONE
```