Extend getXdocsFilePaths to gather .xml.vm files and get rid of getAllXdocFilePaths

[stoyanK7]

In #13362 we add new method in XdocUtil - getAllXdocFilePaths. The method is almost identical to getXdocsFilePaths except that it also gets .xml.vm files.

If we extend getXdocsFilePaths to include .xml.vm files, 3 tests break:

    public static Set<Path> getXdocsFilePaths() throws IOException {
        final Path directory = Paths.get(DIRECTORY_PATH);
        try (Stream<Path> stream = Files.find(directory, Integer.MAX_VALUE,
-                (path, attr) -> attr.isRegularFile() && path.toString().endsWith(".xml"))) {
+                (path, attr) -> {
+                   return attr.isRegularFile()
+                            && path.toString().endsWith(".xml")
+                            || path.toString().endsWith(".xml.vm");
+                })) {
            return stream.collect(Collectors.toSet());
        }
    }

[ERROR] Failures: 
[ERROR]   XdocsMobileWrapperTest.testAllCheckSectionMobileWrapper:67->iterateNode:80 writingjavadocchecks.xml.vm/HTML Code In Javadoc Comments: Tag 'table' in 'section' needs a wrapping <span> or <div> with the class 'wrapper'.
expected any of: [div, span]
but was        : section
[ERROR]   XdocsPagesTest.testAllSubSections:399 index.xml.vm sub-section Inactive / Old Tools for section Related Tools must match
expected: Related_Tools_Inactive_/_Old_Tools
but was : Related_Tools_Inactive_Old_Tools
[ERROR] Errors: 
[ERROR]   XdocsPagesTest.testAllXmlExamples:431->isValidCheckstyleXml:507 Checkstyle writingjavadocchecks.xml.vm has invalid Checkstyle xml (unable to parse configuration stream - Element type "audio" must be declared.:5:8): <audio><source src="horse.ogg" type="audio/ogg"/></audio>
[INFO] 
[ERROR] Tests run: 4202, Failures: 2, Errors: 1, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE

[nrmancuso]

Closed via #13395