Move to Zulu JRE (#1675)

* Move `apt` commands behind `$CI`

Same as for the windows command, no need to rerun this every time

* Use fallback to avoid unbound variables

* Scripts: Switch to Zulu JRE

* workflows: Switch to zulu JDK

* fix: Launcher requires sun.awt.* exports

* Update renovate for Zulu

.github/workflows/build_pull_request.yml

@@ -48,7 +48,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           java-version: 21
-          distribution: 'temurin'
+          distribution: 'zulu'
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v4
@@ -94,4 +94,4 @@ jobs:
             printf "exit code '%s' - exiting.\n" "$ecode"
             exit "$ecode"
           fi
-          exit 0
+          exit 0