fix bazel_to_go.py for setting up vendor directory (#1806)
fix bazel_to_go.py for setting up vendor directory (#1806)

Automatic merge from submit-queue.

fix bazel_to_go.py for setting up vendor directory

- aws/aws-go-sdk in WORKSPACE: the same repository is already
  referred above, with a different name. This entry is just
  redundant, and confuses bazel_to_go.py script, so removed.
- istio.io/api: this repository seems not in as a standard
  go_repository() declarations, manually added to bazel_to_go.

additionally, some mixer/ files are changed due to a run of
bazel_to_go.py itself, synchronization of the generated files.

**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 #

**Special notes for your reviewer**:

**Release note**:

```release-note
```
istio/pkg,istio/pkg,istio/pkg,istio/pkg,istio/pkg