Strip carriage-return characters in expected output for ReleaseNotesGeneratorTest.

The template generator also strips these, so we need to do so to make this pass
on Windows.

Note that we use replace("\r", "") where the template generator uses
replace("\\r", ""). The latter didn't work for me when I tried it on Windows,
for reasons I'm not aware of.

Author: prdoyle

build-tools-internal/src/test/java/org/elasticsearch/gradle/internal/release/ReleaseNotesGeneratorTest.java

@@ -184,7 +184,7 @@ private ChangelogEntry makeHighlightsEntry(int pr, boolean notable) {
     }
 
     private String getResource(String name) throws Exception {
-        return Files.readString(Paths.get(Objects.requireNonNull(this.getClass().getResource(name)).toURI()), StandardCharsets.UTF_8);
+        return Files.readString(Paths.get(Objects.requireNonNull(this.getClass().getResource(name)).toURI()), StandardCharsets.UTF_8).replace("\r", "");
     }
 
     private void writeResource(String name, String contents) throws Exception {