feat(functions): upgrade to java25 runtime

*  Compiler Compatibility: The maven.compiler.source and maven.compiler.target properties in pom.xml needed to be updated from 11 to 25.
* Parent Configuration: The shared-configuration parent POM was updated to version 1.2.2 to align with newer Java runtime
      samples.
* Plugin Updates: The jacoco-maven-plugin version 0.8.7 does not support Java 25 (major version 69). It was necessary to
      explicitly add version 0.8.14 to the pom.xml to resolve build failures during test coverage reporting.

 [INFO] -------------------------------------------------------                                                            │
│ [INFO]  T E S T S                                                                                                         │
│ [INFO] -------------------------------------------------------                                                            │
│ [INFO] Running functions.HelloWorldTest                                                                                   │
│ [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.807 s -- in functions.HelloWorldTest             │
│ [INFO]                                                                                                                    │
│ [INFO] Results:                                                                                                           │
│ [INFO]                                                                                                                    │
│ [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0                                                                   │
│ [INFO]                                                                                                                    │
│ [INFO] ------------------------------------------------------------------------                                           │
│ [INFO] BUILD SUCCESS                                                                                                      │
│ [INFO] ------------------------------------------------------------------------                                           │
│ [INFO] Total time:  9.410 s                                                                                               │
│ [INFO] Finished at: 2025-12-19T09:01:21Z                                                                                  │
│ [INFO] ------------------------------------------------------------------------

Author: iennae

functions/helloworld/helloworld/pom.xml

@@ -32,7 +32,7 @@
   <parent>
     <groupId>com.google.cloud.samples</groupId>
     <artifactId>shared-configuration</artifactId>
-    <version>1.2.0</version>
+    <version>1.2.2</version>
   </parent>
 
   <dependencyManagement>
@@ -50,8 +50,8 @@
   <!-- [START functions_example_pom] -->
   <!-- [START functions_example_pom_dependencies] -->
   <properties>
-    <maven.compiler.target>11</maven.compiler.target>
-    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>25</maven.compiler.target>
+    <maven.compiler.source>25</maven.compiler.source>
   </properties>
 
   <dependencies>
@@ -92,6 +92,25 @@
 
   <build>
     <plugins>
+      <plugin>
+        <groupId>org.jacoco</groupId>
+        <artifactId>jacoco-maven-plugin</artifactId>
+        <version>0.8.14</version>
+        <executions>
+          <execution>
+            <goals>
+              <goal>prepare-agent</goal>
+            </goals>
+          </execution>
+          <execution>
+            <id>report</id>
+            <phase>prepare-package</phase>
+            <goals>
+              <goal>report</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
       <!-- [START functions_maven_specify_function] -->
       <plugin>
         <!-- [END functions_maven_specify_function] -->