Require JDK 8 on CI?

XML output changed between JDK 8 and JDK 11, breaking some unit tests.

Constrain CI to using JDK 8, so that tests pass.

Author: jonpryor

build-tools/automation/azure-pipelines.yaml

@@ -108,10 +108,10 @@ jobs:
 
   - template: templates\install-dependencies.yaml
 
-  - script: make prepare CONFIGURATION=$(Build.Configuration) JI_MAX_JDK=11
+  - script: make prepare CONFIGURATION=$(Build.Configuration) JI_MAX_JDK=8
     displayName: make prepare
 
-  - script: make all CONFIGURATION=$(Build.Configuration) JI_MAX_JDK=11
+  - script: make all CONFIGURATION=$(Build.Configuration) JI_MAX_JDK=8
     displayName: make all
 
   - script: |