This commit changes the tests added in #45383 so that the fixture that
emulates the S3 service now sometimes consumes all the request body
before sending an error, sometimes consumes only a part of the request
body and sometimes consumes nothing. The idea here is to beef up a bit
the tests that writes blob because the client's retry logic relies on
marking and resetting the blob's input stream.
This pull request also changes the testWriteBlobWithRetries() so that it
(rarely) tests with a large blob (up to 1mb), which is more than the client's
default read limit on input streams (131Kb).
Finally, it optimizes the ZeroInputStream so that it is a bit more effective
(now works using an internal buffer and System.arraycopy() primitives).
aee92d573c