feat(sql): Add SQL index on createdon field

[pedro93]

Adds a MySQL index on the createdon column to allow for faster filtering based on time.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions]

Unit Test Results (build & test)

621 tests  +250   617 ✔️ +246   15m 44s ⏱️ + 14m 45s
157 suites +  55       4 💤 +    4 
157 files   +  55       0 ❌ ±    0 

Results for commit 9473621. ± Comparison against base commit 7f71b25.

♻️ This comment has been updated with latest results.

[jjoyce0510]

@pedro93 This will only impact new deployments, correct?

[pedro93]

@pedro93 This will only impact new deployments, correct?

Yes for MySQL. For the rest the create statement always executes when the setup job runs which is always with our helm chart.