Remove the hard-coded cache tag in CasRedirectData

Problem/Motivation

The CasRedirectData->cacheTags property has a hard-coded cache tag 'config:cas.settings'.

In 🐛 Redirect response should get cache tags from overridden config Active we change the code to use the cache tags / metadata from the config object.
With this change, the default tag in CasRedirectData->cacheTags property is no longer needed for this module to work.
However, there might be 3rd party code that relies on the default cache tag being present.

Furthermore, the entire property and the ->setCacheTags() could be removed, and the module would still work.
Again, there could be 3rd party code that uses it.

Steps to reproduce

Remove the default tag.
Remove the property and methods.
Run tests and verify they still work.

Proposed resolution

Remove the default tag.
Remove the property and methods.

To not have to worry about BC, this should perhaps happen in a major version upgrade, so 4.x.
But this depends on how committed we are to support 3rd party code that uses CasRedirectData directly.

Remaining tasks

User interface changes

API changes

The CasRedirectData->setCacheTags() and ->getCacheTags() are gone.

Data model changes