Revert "Add SearchValues<char> implementation for two sets of 128 chars (#103…" (#105562)

This reverts commit 13abb44.

Author: stephentoub

src/libraries/System.Memory/tests/Span/SearchValues.cs

@@ -82,7 +82,6 @@ public static IEnumerable<object[]> Values_MemberData()
             {
                 yield return Pair(value);
                 yield return Pair('a' + value);
-                yield return Pair('\uFF00' + value);
 
                 // Test some more duplicates
                 if (value.Length > 0)

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -441,7 +441,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any1SearchValues.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any2SearchValues.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\Any3SearchValues.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\AsciiWithSecondSetCharSearchValues.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\BitVector256.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\ProbabilisticMapState.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\SearchValues\ProbabilisticWithAsciiCharSearchValues.cs" />