Automatic merge from submit-queue

cluster/aws: Clean up dhcp-options

**What this PR does / why we need it**: After adding the aws janitor, the thing we're consistently sweeping is the DhcpOptionSets created by cluster/aws/util.sh (and there were thousands on the first run). Fix it!

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*:
**Special notes for your reviewer**:
**Release note**:
```release-note
Fix an issue where AWS tear-down leaks an DHCP Option Set.
```