Use issue tracker data tables for reading & storing data

What does this MR do?

It starts using data_fields (jira_tracker_data for Jira and issue_tracker_data for other issue trackers).

• it reads data from both properties and data fields
• it creates new data and updates data only in data_fields tables

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Performance and testing

If cross-browser testing is not required, please remove the relevant item, or mark it as not needed: [-] -->

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

#63082 (moved)