[iOS] Reenable skipped StructureToPtr tests (#73236)

As a result of #73013 landing, the skipped StructureToPtr tests can be enabled.

Contributes to #73008

src/libraries/System.Runtime.InteropServices/tests/System.Runtime.InteropServices.UnitTests/System/Runtime/InteropServices/Marshal/PtrToStructureTests.cs

@@ -13,7 +13,6 @@ namespace System.Runtime.InteropServices.Tests
     public class PtrToStructureTests
     {
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/73008", TestPlatforms.iOS | TestPlatforms.tvOS)]
         public void StructureToPtr_NonGenericType_ReturnsExpected()
         {
             var structure = new SequentialClass
@@ -65,7 +64,6 @@ public void StructureToPtr_GenericType_ReturnsExpected()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/73008", TestPlatforms.iOS | TestPlatforms.tvOS)]
         public void StructureToPtr_NonGenericObject_ReturnsExpected()
         {
             var structure = new SomeTestStruct
@@ -92,7 +90,6 @@ public void StructureToPtr_NonGenericObject_ReturnsExpected()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/73008", TestPlatforms.iOS | TestPlatforms.tvOS)]
         public void StructureToPtr_GenericObject_ReturnsExpected()
         {
             var structure = new SomeTestStruct
@@ -149,7 +146,6 @@ public void PtrToStructure_AutoLayoutClass_ThrowsArgumentException()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/73008", TestPlatforms.iOS | TestPlatforms.tvOS)]
         public unsafe void PtrToStructure_GenericLayoutClass_Generic()
         {
             int i = 42;
@@ -160,7 +156,6 @@ public unsafe void PtrToStructure_GenericLayoutClass_Generic()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/73008", TestPlatforms.iOS | TestPlatforms.tvOS)]
         public unsafe void PtrToStructure_GenericLayoutClass()
         {
             int i = 42;