Manually handle open/close of upload file.
Manually handle open/close of upload file.

  * The context manager adds useless overhead.

Change-Id: I1dce123b043237084a53a88e8d750fd990b7a6d8

kernelci/kernelci-backend,joyxu/kernelci-backend,kernelci/kernelci-backend,joyxu/kernelci-backend,joyxu/kernelci-backend