Fix A11y test calling thread bug, enable threading lint for tests

Fixes all lint warnings in AccessibilityDelegateCompatTest.

Baselines threading issue in wear-watchface for future mass bug filing.

Relnote: Added explicit threading annotation for setImportantForAccessibility
Bug: 195144502
Test: AccessibilityDelegateCompatTest
Test: ./gradlew lintDebug
Change-Id: I990faac25c6136591f97c8d4cdea0b3372f51af2
diff --git a/buildSrc/lint.xml b/buildSrc/lint.xml
index 1fb6d32..0d38ee1 100644
--- a/buildSrc/lint.xml
+++ b/buildSrc/lint.xml
@@ -13,6 +13,7 @@
         <!-- Required for AppSearch icing tests. -->
         <ignore path="**/java/tests/**" />
     </issue>
-    <!-- Re-enable NewApi for tests (and everything else). -->
+    <!-- Re-enable high-priority checks for tests (and everything else). -->
     <issue id="NewApi" severity="fatal" />
+    <issue id="WrongThread" severity="fatal" />
 </lint>