Fix ESIndexInputTestCase#randomReadAndSlice (#93227)

In #93205 we fixed a bug in `ByteArrayIndexInput` but accidentally
reduced the coverage of the test suite with a supposedly-temporary
change for debugging purposes. This commit brings the test suite back up
to full strength again.

This was fixed in `main` by #93208, but most of that change is not for
backporting.

test/framework/src/main/java/org/elasticsearch/common/lucene/store/ESIndexInputTestCase.java

@@ -62,7 +62,7 @@ protected byte[] randomReadAndSlice(IndexInput indexInput, int length) throws IO
         int readPos = (int) indexInput.getFilePointer();
         byte[] output = new byte[length];
         while (readPos < length) {
-            final var readStrategy = randomFrom(2, 6);
+            final var readStrategy = between(0, 8);
             switch (readStrategy) {
                 case 0, 1, 2, 3:
                     if (length - readPos >= Long.BYTES && readStrategy <= 0) {