fix: Get actual data type of presto columns (that have precision) in sql lab schema listing

[tooptoop4]

SQLLab fix for "Schema on the left shows datatype of OTHER instead of varchar(40) or decimal(38,18)

log has
2020-03-26 00:13:10,188:INFO:root:Did not recognize type varchar(300) of column country_name
2020-03-26 00:13:10,188:INFO:root:Did not recognize type varchar(40) of column ccn"

[codecov-commenter]

Codecov Report

Merging #9896 into master will decrease coverage by 0.11%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #9896      +/-   ##
==========================================
- Coverage   71.25%   71.13%   -0.12%     
==========================================
  Files         584      584              
  Lines       30809    30665     -144     
  Branches     3238     3238              
==========================================
- Hits        21953    21814     -139     
+ Misses       8746     8740       -6     
- Partials      110      111       +1     

Flag	Coverage Δ
#cypress	53.82% <ø> (-0.03%)	⬇️
#javascript	59.44% <ø> (ø)
#python	71.21% <100.00%> (-0.19%)	⬇️

Impacted Files	Coverage Δ
superset/db_engine_specs/presto.py	70.41% <100.00%> (+0.06%)	⬆️
superset/views/tags.py	35.13% <0.00%> (-4.11%)	⬇️
superset/views/sql_lab.py	59.06% <0.00%> (-3.29%)	⬇️
superset/cli.py	36.72% <0.00%> (-3.14%)	⬇️
superset/views/api.py	63.63% <0.00%> (-2.08%)	⬇️
superset/views/dashboard/views.py	67.74% <0.00%> (-1.96%)	⬇️
superset/views/core.py	75.16% <0.00%> (-0.90%)	⬇️
superset/views/chart/views.py	86.48% <0.00%> (-0.70%)	⬇️
superset-frontend/src/SqlLab/actions/sqlLab.js	66.15% <0.00%> (-0.66%)	⬇️
superset/connectors/sqla/views.py	76.98% <0.00%> (-0.54%)	⬇️
... and 18 more

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[tooptoop4]

maybe superseded by #10658

[villebro]

@tooptoop4 sorry for not having noticed this before! Are you ok with closing this in favor of the other PR, as that does some additional refactoring + adds tests?