If `SkipReader` is called with a small initial buffer it may be doing a huge number if Reads to skip the requested number of bytes. If a small buffer is provided grab a 32K buffer and use that.
Fixes slow execution of `testAPIGetObjectWithMPHandler`.
Bonuses:
* Use `-short` with `-race` test.
* Do all suite test types with `-short`.
* Enable compressed+encrypted in `testAPIGetObjectWithMPHandler`.
* Disable big file tests in `testAPIGetObjectWithMPHandler` when using `-short`.
2040559f71