Use Random from LuceneTestCase for repeatable results

Author: paulirwin

src/Lucene.Net.Tests.Analysis.Common/Support/Analysis/Util/TestOpenStringBuilderBufferWriter.cs

@@ -468,13 +468,12 @@ protected static void WriteData(IBufferWriter<char> bufferWriter, int numChars)
         {
             Span<char> outputSpan = bufferWriter.GetSpan(numChars);
             Debug.Assert(outputSpan.Length >= numChars);
-            var random = new Random(42);
 
             var data = new char[numChars];
 
             for (int i = 0; i < numChars; i++)
             {
-                data[i] = (char)random.Next(0, char.MaxValue);
+                data[i] = (char)Random.Next(0, char.MaxValue);
             }
 
             data.CopyTo(outputSpan);

src/Lucene.Net.Tests/Support/Analysis/TokenAttributes/TestCharTermAttributeImplBufferWriter.cs

@@ -425,13 +425,12 @@ protected static void WriteData(IBufferWriter<char> bufferWriter, int numChars)
         {
             Span<char> outputSpan = bufferWriter.GetSpan(numChars);
             Debug.Assert(outputSpan.Length >= numChars);
-            var random = new Random(42);
 
             var data = new char[numChars];
 
             for (int i = 0; i < numChars; i++)
             {
-                data[i] = (char)random.Next(0, char.MaxValue);
+                data[i] = (char)Random.Next(0, char.MaxValue);
             }
 
             data.CopyTo(outputSpan);