Some s3api functional tests were setting boto logging level to DEBUG,
which results in a very large amount of logging output from the test
runner, including large request bodies. This makes it extremely hard
to inspect test output.
This patch makes the quiet_boto_logging context manager revert the
logger level to its original value rather than indiscriminately
leaving it set to DEBUG.
Change-Id: I1dd9603adf9a19e89da5a461d3c6810a3432ae46
60c0ab2ea0