Disable XSL tests that fail inconsistently (dotnet/corefx#14898)

Commit migrated from https://github.com/dotnet/corefx/commit/63dd90b2d8ff169cb18e860073af054c54987241

src/libraries/System.Private.Xml/tests/Xslt/XslCompiledTransformApi/Errata4.cs

@@ -183,6 +183,7 @@ public void CreateElementsAndAttributesUsingXsltAndXPath(object param0, object p
             return;
         }
 
+        [ActiveIssue(14772)]
         //[Variation(Priority = 1, Desc = "Crate elment/attribute (Inline) :: Invalid start name char", Params = new object[] { false, CharType.NameStartChar })]
         [InlineData(false, CharType.NameStartChar)]
         //[Variation(Priority = 1, Desc = "Crate elment/attribute (Inline) :: Invalid name char", Params = new object[] { false, CharType.NameChar })]
@@ -266,6 +267,7 @@ private string GenerateStringToInject(string charsToChooseFrom, int position, Ch
             }
         }
 
+        [ActiveIssue(14775)]
         //[Variation(Priority = 1, Desc = "Invalid start name char", Params = new object[] { false, CharType.NameStartChar })]
         [InlineData(false, CharType.NameStartChar)]
         //[Variation(Priority = 1, Desc = "Invalid name char", Params = new object[] { false, CharType.NameChar })]