Fix REXML compatibility issues for Ruby 3.4

- Update TomcatGeodeStore to properly create XML documents with REXML
- Ruby 3.4's REXML no longer allows creating documents with just XML declaration
- Remove trailing whitespace from XML fixture files (REXML Pretty formatter now strips these)
- All 972 non-integration tests now passing

Author: ramonskie

lib/java_buildpack/container/tomcat/tomcat_geode_store.rb

@@ -129,7 +129,8 @@ def cache_client_xml_path
       end
 
       def create_cache_client_xml
-        document = REXML::Document.new('<?xml version="1.0" encoding="UTF-8"?>')
+        document = REXML::Document.new
+        document << REXML::XMLDecl.new('1.0', 'UTF-8')
         add_client_cache document
         write_xml cache_client_xml_path, document
       end

spec/fixtures/container_no_tomcat_version_geode_store_context_after.xml

@@ -14,7 +14,7 @@
   ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
-  --> 
+  -->
 <Context allowLinking='true'>
     <Manager className='org.apache.geode.modules.session.catalina.TomcatDeltaSessionManager' enableLocalCache='true' regionAttributesId='PARTITION_REDUNDANT_HEAP_LRU'/>
 </Context>

spec/fixtures/container_tomcat_geode_store_context_after.xml

@@ -14,7 +14,7 @@
   ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
-  --> 
+  -->
 <Context allowLinking='true'>
     <Manager className='org.apache.geode.modules.session.catalina.Tomcat9DeltaSessionManager' enableLocalCache='true' regionAttributesId='PARTITION_REDUNDANT_HEAP_LRU'/>
 </Context>

spec/fixtures/container_tomcat_redis_store_context_after.xml

@@ -14,7 +14,7 @@
   ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
-  --> 
+  -->
 <Context allowLinking='true'>
     <Valve className='com.gopivotal.manager.SessionFlushValve'/>
     <Manager className='org.apache.catalina.session.PersistentManager'>