NO-JIRA: GHA workflow improvements

- Build examples using release profile on JDK8, like the Travis job.
- Build the examples on JDK11+ (unlike the Travis job).
- Add a workflow_dispatch trigger to allow manual start of new runs
  without using the rerun button and overrwriting previous logs.

.github/workflows/build.yml

@@ -1,6 +1,6 @@
 name: "Build"
 
-on: [push, pull_request]
+on: [push, pull_request, workflow_dispatch]
 
 jobs:
   build:
@@ -32,8 +32,15 @@ jobs:
       - name: Build Main
         run: |
           mvn -Dorg.apache.activemq.artemis.core.io.aio.AIOSequentialFileFactory.DISABLED=AnythingNotNull -Djdk8-errorprone -Pfast-tests -Pextra-tests -Ptests-CI -Pjmh install
-      - name: Build Examples
+
+      - name: Build Examples (JDK8 / -Prelease)
+        if: matrix.java == '8'
         run: |
           cd examples
-          mvn install -PnoRun
+          mvn install -Prelease
 
+      - name: Build Examples (JDK 11+ / -Pexamples,noRun)
+        if: matrix.java != '8'
+        run: |
+          cd examples
+          mvn install -Pexamples,noRun