Enable connector dropdown in integration tab when null and undefined

[Kelsey-Ethyca]

Closes #3588

Code Changes

• add to disabled check that connectionConfig is defined and not null

Steps to Confirm

• create a new system
• after clicking save immediately navigate to the integration tab
• verify the connection type dropdown is enabled

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation:
  • documentation complete, PR opened in fidesdocs
  • documentation issue created in fidesdocs
• Issue Requirements are Met
• Relevant Follow-Up Issues Created
• Update CHANGELOG.md
• For API changes, the Postman collection has been updated

Description Of Changes

Write some things here about the changes and any potential caveats

[cypress]

Passing run #2772 ↗︎

0	4	0	0	0
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Details:

Merge c460e3c into 9cddb24...
Project: fides	Commit: 597cb4cec2 ℹ️
Status: Passed	Duration: 00:46 💡
Started: Jun 19, 2023 4:37 AM	Ended: Jun 19, 2023 4:38 AM

_{This comment has been generated by cypress-bot as a result of this project's GitHub integration settings.}