Use pandas' transpose when the data is expected to be small.

[ueshin]

As per the discussion #1927 (comment), we should just use pandas' transpose when the expected data size is small enough.

[codecov-io]

Codecov Report

Merging #1932 (867df66) into master (86aa350) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1932   +/-   ##
=======================================
  Coverage   94.17%   94.17%           
=======================================
  Files          41       41           
  Lines       10053    10053           
=======================================
  Hits         9467     9467           
  Misses        586      586           

Impacted Files	Coverage Δ
databricks/koalas/frame.py	96.67% <100.00%> (ø)
databricks/koalas/series.py	97.04% <100.00%> (ø)

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