Harshavardhana 1330e59307
accessKeyId missing should return appropriate error in AssumeRole (#9048)
For a non-existent user server would return STS not initialized
```
aws --profile harsha --endpoint-url http://localhost:9000 \
      sts assume-role \
      --role-arn arn:xxx:xxx:xxx:xxxx \
      --role-session-name anything
```

instead return an appropriate error as expected by STS API

Additionally also format the `trace` output for STS APIs
2020-02-26 12:26:47 -08:00
..
2020-01-31 08:29:22 +05:30
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2020-01-31 08:29:22 +05:30
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