Disable 2 System.Drawing tests for TailcallStress (#38891)

Issue: #38889

Author: BruceForstall

src/libraries/System.Drawing.Common/tests/FontTests.cs

@@ -784,6 +784,7 @@ public void SizeInPoints_Get_ReturnsExpected(GraphicsUnit unit)
         [InlineData(FontStyle.Strikeout | FontStyle.Bold | FontStyle.Italic, 255, true, "@", 700)]
         [InlineData(FontStyle.Regular, 0, false, "", 400)]
         [InlineData(FontStyle.Regular, 10, false, "", 400)]
+        [SkipOnCoreClr("https://github.com/dotnet/runtime/issues/38889", RuntimeTestModes.TailcallStress)]
         public void ToLogFont_Invoke_ReturnsExpected(FontStyle fontStyle, byte gdiCharSet, bool gdiVerticalFont, string expectedNamePrefix, int expectedWeight)
         {
             using (FontFamily family = FontFamily.GenericMonospace)
@@ -817,6 +818,7 @@ public void ToLogFont_Invoke_ReturnsExpected(FontStyle fontStyle, byte gdiCharSe
         [InlineData(TextRenderingHint.SingleBitPerPixel)]
         [InlineData(TextRenderingHint.SingleBitPerPixelGridFit)]
         [InlineData(TextRenderingHint.ClearTypeGridFit)]
+        [SkipOnCoreClr("https://github.com/dotnet/runtime/issues/38889", RuntimeTestModes.TailcallStress)]
         public void ToLogFont_InvokeGraphics_ReturnsExpected(TextRenderingHint textRenderingHint)
         {
             using (FontFamily family = FontFamily.GenericMonospace)