Update test_tf_cifar.py

[mvsusp]

Reduce number of training steps of this test.

Merge Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your pull request.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have updated the changelog with a description of my changes (if appropriate)
• I have updated any necessary documentation (if appropriate)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-io]

Codecov Report

Merging #146 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #146   +/-   ##
=======================================
  Coverage   90.27%   90.27%           
=======================================
  Files          36       36           
  Lines        2438     2438           
=======================================
  Hits         2201     2201           
  Misses        237      237

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 524dc86...9ece54a. Read the comment docs.

[nadiaya]

Thanks!

[ChoiByungWook]

Closing in lieu of #160.