fix(presto,trino): use correct literal dttm separator

[villebro]

SUMMARY

#19917 migrated the convert_dttm functions in the Presto and Trino db engine specs to use the currently recommended literal timestamp type cast over the now deprecated from_iso8601_* functions. However, the new literal casts require the separator to be a blank space instead of the "T" separator:

• https://trino.io/docs/current/functions/datetime.html
• https://prestodb.io/docs/current/functions/datetime.html

This PR updates the format to correspond with the supported format and updates the unit tests accordingly. In addition, the convert_dttm tests are removed from the legacy integration test suite, as they're already covered by the new unit tests.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

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 #20123 (da7ee65) into master (1fe30f1) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #20123      +/-   ##
==========================================
- Coverage   66.46%   66.44%   -0.03%     
==========================================
  Files        1721     1721              
  Lines       64467    64477      +10     
  Branches     6795     6795              
==========================================
- Hits        42847    42839       -8     
- Misses      19892    19910      +18     
  Partials     1728     1728              

Flag	Coverage Δ
hive	53.70% <0.00%> (+0.01%)	⬆️
mysql	82.14% <100.00%> (+<0.01%)	⬆️
postgres	?
presto	53.56% <0.00%> (+0.01%)	⬆️
python	82.56% <100.00%> (-0.06%)	⬇️
sqlite	81.94% <100.00%> (+<0.01%)	⬆️
unit	49.40% <100.00%> (+0.01%)	⬆️

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/db_engine_specs/trino.py	71.42% <100.00%> (ø)
superset/sql_validators/postgres.py	50.00% <0.00%> (-50.00%)	⬇️
superset/sql_validators/__init__.py	80.00% <0.00%> (-20.00%)	⬇️
superset/reports/commands/log_prune.py	85.71% <0.00%> (-3.58%)	⬇️
superset/databases/commands/validate_sql.py	92.00% <0.00%> (-2.00%)	⬇️
superset/db_engine_specs/postgres.py	95.45% <0.00%> (-1.82%)	⬇️
superset/commands/importers/v1/utils.py	92.20% <0.00%> (-1.30%)	⬇️
superset/common/query_object.py	94.73% <0.00%> (-0.53%)	⬇️
superset/views/base_api.py	97.97% <0.00%> (-0.41%)	⬇️
... and 5 more

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[nytai]

LGTM, though wondering if the same also applies to athena?

[villebro]

LGTM, though wondering if the same also applies to athena?

Good point, let me check and add Athena, too.

[villebro]

Turns out Athena was already using the space separator, so going to go ahead and merge this.