Add missing tests for datetime & Remove unsupported property

[itholic]

Add missing test for weekday

Remove unsupported property millisecond for Series Datetime Properties.

[softagram-bot]

Softagram Impact Report for pull/729 (head commit: 0e87b72)

⭐ Change Overview

(Open in Softagram Desktop for full details)

📄 Full report

• Permalink: Full report for pull/729

Impact Report explained. Give feedback on this report to [email protected]

[codecov-io]

Codecov Report

Merging #729 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #729      +/-   ##
==========================================
+ Coverage   94.19%   94.23%   +0.03%     
==========================================
  Files          32       32              
  Lines        5567     5564       -3     
==========================================
- Hits         5244     5243       -1     
+ Misses        323      321       -2

Impacted Files	Coverage Δ
databricks/koalas/datetimes.py	98.23% <ø> (+1.67%)	⬆️

---

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 4228bad...0e87b72. Read the comment docs.

[HyukjinKwon]

Why did we remove this? Does this not work?

[itholic]

@HyukjinKwon, Thanks to Review.
I thought these were the reuses of the Pandas Series dt Property.
However, in the screenshots I added to PR, the Pandas Series dt Property does not support milliseconds.
So I thought this was probably added by mistake.
And It doesn't actually work as you asked, (as in the following screenshot.)