Tests: Fix convert error tests to use fixed value

The error tests for hex values previously used a random string of
digits, but this could be a valid hex value. This commit changes these
tests to use a fixed invalid hex value.

closes elastic#32370

modules/ingest-common/src/test/java/org/elasticsearch/ingest/common/ConvertProcessorTests.java

@@ -67,10 +67,9 @@ public void testConvertIntLeadingZero() throws Exception {
         assertThat(ingestDocument.getFieldValue(fieldName, Integer.class), equalTo(10));
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/32370")
     public void testConvertIntHexError() {
         IngestDocument ingestDocument = RandomDocumentPicks.randomIngestDocument(random());
-        String value = "0x" + randomAlphaOfLengthBetween(1, 10);
+        String value = "0xnotanumber";
         String fieldName = RandomDocumentPicks.addRandomField(random(), ingestDocument, value);
         Processor processor = new ConvertProcessor(randomAlphaOfLength(10), fieldName, fieldName, Type.INTEGER, false);
         IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> processor.execute(ingestDocument));
@@ -140,7 +139,7 @@ public void testConvertLongLeadingZero() throws Exception {
 
     public void testConvertLongHexError() {
         IngestDocument ingestDocument = RandomDocumentPicks.randomIngestDocument(random());
-        String value = "0x" + randomAlphaOfLengthBetween(1, 10);
+        String value = "0xnotanumber";
         String fieldName = RandomDocumentPicks.addRandomField(random(), ingestDocument, value);
         Processor processor = new ConvertProcessor(randomAlphaOfLength(10), fieldName, fieldName, Type.LONG, false);
         IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> processor.execute(ingestDocument));