[7.0] Remove LegacyPropertyManagementTrait from User class

[Hackwar]

Summary of Changes

The LegacyPropertyManagementTrait has been deprecated for a long time and will probably be removed in 7.0. This PR removes its inclusion in the User class for Joomla 7.0.

Testing Instructions

Codereview

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org: Removal of LegacyPropertyManagementTrait and CMSObject Manual#615

• No documentation changes for manual.joomla.org needed

[HLeithner]

This pull request has been automatically rebased to 6.1-dev.

[laoneo]

I would say that this is too early as it can break extensions, overrides and custom code.

[Hackwar]

This has been deprecated for 10 years, so I don't see how this would change anything if we wait any longer.

[laoneo]

Better to add a get function to the User class and throw an exception when the compat plugin is disabled.

[laoneo]

Thanks!