Update all CI jobs to use JDK 11

- Updated Integration Tests to use JDK_11
- Updated functions-e2e-tests job to use JDK 11 instead of JDK 8
- Updated functions-sample-tests job to use JDK 11 instead of JDK 8

Regarding Gradle 8.0: Upgrading would require also updating the
protobuf plugin from 0.8.16 to 0.9.x for full compatibility, which
is a larger change that could be done in a separate PR.

Co-authored-by: torosent <17064840+torosent@users.noreply.github.com>

Author: Copilot

.github/workflows/build-validation.yml

@@ -88,7 +88,9 @@ jobs:
       run: sleep 10
 
     - name: Integration Tests with Gradle
-      run: ./gradlew integrationTest || echo "TEST_FAILED=true" >> $GITHUB_ENV
+      run: |
+        export JAVA_HOME=$JDK_11
+        ./gradlew integrationTest || echo "TEST_FAILED=true" >> $GITHUB_ENV
       continue-on-error: true
 
     - name: Kill Durable Task Emulator
@@ -124,11 +126,11 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up JDK 8
+      - name: Set up JDK 11
         uses: actions/setup-java@v2
         with:
-          java-version: '8'
-          distribution: 'temurin'
+          java-version: '11'
+          distribution: 'microsoft'
 
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2
@@ -163,11 +165,11 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Set up JDK 8
+      - name: Set up JDK 11
         uses: actions/setup-java@v2
         with:
-          java-version: '8'
-          distribution: 'temurin'
+          java-version: '11'
+          distribution: 'microsoft'
 
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2