When deleting multiple objects, S3 allows to enable
a quiet mode with the 'Quiet' key.
At AWS S3, the value of this key is case-insensitive.
- Quiet mode is enabled if the value is 'true'
(regardless of case).
- Otherwise, in all other cases (even a non-boolean value),
this mode will be disabled.
Also, some tools (like Minio's python API) send the value 'True'
(and not 'true').
Change-Id: Id9d1da2017b8d13242ae1f410347febb013e9ce1