chore: Java 8 unit test to build code in Java 17 and run tests on Jav…

…a 8 (#1800) (#1227)

* Our Java projects are configured to produce Java 8-compatible bytecode via https://togithub.com/googleapis/java-shared-config/blob/main/pom.xml#L848. This unit test change ensures this config is applied correctly.

* This change also switches the JDK distribution of GitHub Actions to temurin from zulu.

* For the repositories that mark "dependencies (8)" and "dependencies (11)" as required, they should point to only "dependencies (17)" via `.github/sync-repo-settings.yaml` and repo's Settings tab.
Source-Link: https://togithub.com/googleapis/synthtool/commit/cbe010084fc59dc15730c86e9b8e03ddac1de050
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-java:latest@sha256:32851debfefed2b66038e0141f1b5c2103bb59ba80b7475adbc10ef7abab3de7

.github/.OwlBot.lock.yaml

@@ -14,4 +14,3 @@
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-java:latest
   digest: sha256:af2eda87a54601ae7b7b2be5055c17b43ac98a7805b586772db314de8a7d4a1d
-# created: 2023-06-16T02:10:09.149325782Z