fix: dbmodal test connection error timeout

[pkdotson]

SUMMARY

There was an issue where when testing the dbconnection string would not error out after the 30 second timeout because the checking of the connection would happen before the timeout is initiated. This pr solve that issue by ensuring that if error the timeout will be enforced.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

before

after

TESTING INSTRUCTIONS

Go to db connection modal and input an expired db uri. Test the connection by pressing the test connection button and it should error out in ~30 seconds.

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 #20068 (51db23a) into master (c6dd7fe) will decrease coverage by 11.81%.
The diff coverage is 7.14%.

@@             Coverage Diff             @@
##           master   #20068       +/-   ##
===========================================
- Coverage   66.36%   54.55%   -11.82%     
===========================================
  Files        1715     1720        +5     
  Lines       64186    64383      +197     
  Branches     6753     6753               
===========================================
- Hits        42597    35123     -7474     
- Misses      19871    27542     +7671     
  Partials     1718     1718               

Flag	Coverage Δ
hive	53.69% <7.14%> (+0.01%)	⬆️
mysql	?
postgres	?
presto	53.54% <7.14%> (+0.01%)	⬆️
python	57.98% <7.14%> (-24.52%)	⬇️
sqlite	?
unit	49.39% <7.14%> (+0.25%)	⬆️

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

Impacted Files	Coverage Δ
superset/databases/commands/test_connection.py	32.43% <7.14%> (-67.57%)	⬇️
superset/utils/dashboard_import_export.py	0.00% <0.00%> (-100.00%)	⬇️
superset/key_value/commands/upsert.py	0.00% <0.00%> (-89.59%)	⬇️
superset/key_value/commands/update.py	0.00% <0.00%> (-89.37%)	⬇️
superset/key_value/commands/delete.py	0.00% <0.00%> (-85.30%)	⬇️
superset/key_value/commands/delete_expired.py	0.00% <0.00%> (-80.77%)	⬇️
superset/dashboards/commands/importers/v0.py	15.62% <0.00%> (-76.25%)	⬇️
superset/datasets/commands/update.py	25.88% <0.00%> (-68.24%)	⬇️
superset/datasets/commands/create.py	30.18% <0.00%> (-67.93%)	⬇️
superset/datasets/commands/importers/v0.py	24.03% <0.00%> (-67.45%)	⬇️
... and 282 more

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[betodealmeida]

Looks great!