fix(presto): use milliseconds timespec for presto

[mohittt8]

SUMMARY

Presto does not support microsecond. There is an open ticket to support microsecond/nanosecond for Presto(prestodb/presto#13063)
#19917 removed the from_iso8601_* functions but didn't change the timespec.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

Updated the testcases

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #20333 (4e4a51e) into master (eab0009) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #20333      +/-   ##
==========================================
+ Coverage   66.49%   66.60%   +0.10%     
==========================================
  Files        1734     1734              
  Lines       64996    64996              
  Branches     6871     6871              
==========================================
+ Hits        43219    43288      +69     
+ Misses      20020    19951      -69     
  Partials     1757     1757              

Flag	Coverage Δ
hive	53.70% <0.00%> (?)
mysql	82.28% <100.00%> (ø)
postgres	82.35% <100.00%> (ø)
presto	53.56% <0.00%> (ø)
python	82.78% <100.00%> (+0.21%)	⬆️
sqlite	82.09% <100.00%> (ø)
unit	50.15% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/db_engine_specs/presto.py	88.70% <100.00%> (ø)
superset/utils/core.py	90.14% <0.00%> (+0.11%)	⬆️
superset/connectors/sqla/models.py	90.23% <0.00%> (+0.18%)	⬆️
superset/db_engine_specs/base.py	88.42% <0.00%> (+0.33%)	⬆️
superset/db_engine_specs/hive.py	85.87% <0.00%> (+15.64%)	⬆️
superset/db_engines/hive.py	85.18% <0.00%> (+85.18%)	⬆️

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