[SPARK-51526] Upgrade Gradle shadow plugin to 8.3.6

### What changes were proposed in this pull request?

Migrate the Gradle plugin given it's changed ownership and upgrade Gradle shadow plugin to 8.3.6

### Why are the changes needed?

GradleUp/shadow#908

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

Tested the build locally

### Was this patch authored or co-authored using generative AI tooling?

No

Closes #168 from jacobsalway/SPARK-45923.

Authored-by: Jacob Salway <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>

Author: jacobsalway

gradle/libs.versions.toml

@@ -37,7 +37,7 @@ spotbugs-plugin = "6.0.17"
 spotless-plugin = "6.25.0"
 
 # Packaging
-shadow-jar-plugin = "8.1.1"
+shadow-jar-plugin = "8.3.6"
 
 [libraries]
 kubernetes-client = { group = "io.fabric8", name = "kubernetes-client", version.ref = "fabric8" }
@@ -67,4 +67,4 @@ junit-platform-launcher = { group = "org.junit.platform", name = "junit-platform
 powermock-core = { group = "org.powermock", name = "powermock-core", version.ref = "powermock"}
 spotbugs-gradle-plugin = { group = "com.github.spotbugs.snom", name = "spotbugs-gradle-plugin", version.ref = "spotbugs-plugin" }
 spotless-plugin-gradle = { group = "com.diffplug.spotless", name = "spotless-plugin-gradle", version.ref = "spotless-plugin" }
-shadow = { group = "com.github.johnrengelman", name = "shadow", version.ref = "shadow-jar-plugin"}
+shadow = { group = "com.gradleup.shadow", name = "shadow-gradle-plugin", version.ref = "shadow-jar-plugin"}

spark-operator/build.gradle

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-apply plugin: 'com.github.johnrengelman.shadow'
+apply plugin: 'com.gradleup.shadow'
 
 dependencies {
   implementation project(":spark-operator-api")