Automatic merge from submit-queue
bump QEMU version to v2.9.1
**What this PR does / why we need it**:
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
xref #38067
**Special notes for your reviewer**:
/assign @luxas
**Release note**:
```release-note
update QEMU version to v2.9.1
```
Automatic merge from submit-queue (batch tested with PRs 50602, 51561, 51703, 51748, 49142)
Use arm32v7|arm64v8 images instead of the deprecated armhf|aarch64 image organizations
**What this PR does / why we need it**:
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#50601
**Special notes for your reviewer**:
/assign @ixdy @jbeda @zmerlynn
**Release note**:
```release-note
Use arm32v7|arm64v8 images instead of the deprecated armhf|aarch64 image organizations
```
We can then avoid the following warning:
```
WARNING: The '--' argument must be specified between gcloud specific args on the left and DOCKER_ARGS on the right. IMPORTANT: previously, commands allowed the omission of the --, and unparsed arguments were treated as implementation args. This usage is being deprecated and will be removed in March 2017.
This will be strictly enforced in March 2017. Use 'gcloud beta docker' to see new behavior.
```
Signed-off-by: Jess Frazelle <acidburn@google.com>
