[CI] Set "WearOS Tests" parallelization to 2 agents. (#9639)

The "WearOS Test" job regularly takes over an hour to complete.  Split
the tests it runs into 2 parallel jobs to reduce the time taken to
complete the stage.

Author: jpobst

build-tools/automation/yaml-templates/stage-msbuild-emulator-tests.yaml

@@ -81,7 +81,7 @@ stages:
     timeoutInMinutes: 180
     cancelTimeoutInMinutes: 2
     strategy:
-      parallel: 1
+      parallel: 2
     variables:
       avdApiLevel: 30
       avdAbi: x86