Remove obsolete RemoveAttributesBase from Microsoft.Android.Sdk.ILLink

[Copilot]

Microsoft.Android.Sdk.ILLink still carried RemoveAttributesBase even though nothing in the project derives from or references it. This change removes the dead linker substep to keep the ILLink surface smaller and easier to navigate.

• Scope

  • Delete src/Microsoft.Android.Sdk.ILLink/RemoveAttributesBase.cs

• Impact

  • Removes an unused abstract base type and its attribute-walking logic
  • Leaves the project layout and compiled behavior unchanged aside from dropping the unreferenced code

• Result

  • Reduces maintenance overhead in the ILLink implementation
  • Avoids keeping around a linker extension point that is no longer part of the active codepath

[Copilot]

Pull request overview

This PR removes a dead ILLink substep base class from Microsoft.Android.Sdk.ILLink to reduce the surface area and maintenance burden of the custom linker step assembly.

Changes:

• Deleted the unused RemoveAttributesBase abstract BaseSubStep implementation and its attribute-walking removal logic.

Comments suppressed due to low confidence (1)

src/Microsoft.Android.Sdk.ILLink/RemoveAttributesBase.cs:1

• Removing RemoveAttributesBase deletes a public type from Microsoft.Android.Sdk.ILLink, which is shipped as a tooling assembly (.../tools/Microsoft.Android.Sdk.ILLink.dll) and could be referenced by out-of-tree custom linker steps. If this is intended, it should be treated as an API break (e.g., documented in release notes) or softened by keeping a deprecated shim type (e.g., an [Obsolete] stub) for one release to preserve binary/source compatibility.