OSS header errors don't agree with spec

`src/common/paths/query_analyze.yml` contains

```yaml
default:
description: Internal server error
headers:
X-Influx-Error:
description: A string that describes the problem.
schema:
type: string
X-Influx-Reference:
description: The numeric reference code for the error type.
schema:
type: integer
```

but I don't see either of those error headers returned by OSS; I only see `X-Platform-Error-Code`.

We need to compare this with Cloud and then fix the spec or document the differences.
For now, I've added it as an additional header:

```yaml
default:
description: Internal server error
headers:
X-Platform-Error-Code:
description: The reason for the error.
schema:
type: string
example: "internal error"
X-Influx-Error:
description: A string that describes the problem.
schema:
type: string
X-Influx-Reference:
description: The numeric reference code for the error type.
schema:
type: integer
```