Revert "Update to Checkstyle 8.7"

Yay regressions. Turns out new checkstyle does not handle static import grouping well.

Bug: 72704492

This reverts commit 2e2a9ab615c555c09bd4991e87cadb62594d3c9b.

Change-Id: Icf0e6bf1ee327cb642bc7f121414e76b276edcb6
diff --git a/checkstyle.jar b/checkstyle.jar
index 9ccb44b..747b3e3 100644
--- a/checkstyle.jar
+++ b/checkstyle.jar
Binary files differ
diff --git a/default-treewalker-checks.xml b/default-treewalker-checks.xml
index f86f1dc..8ae9f56 100644
--- a/default-treewalker-checks.xml
+++ b/default-treewalker-checks.xml
@@ -210,6 +210,7 @@
 <module name="OuterTypeFilename">
   <property name="severity" value="error"/>
 </module>
+<module name="FileContentsHolder"/>
 <module name="SuppressionCommentFilter">
   <property name="offCommentFormat" value="CHECKSTYLE:OFF IndentationCheck"/>
   <property name="onCommentFormat" value="CHECKSTYLE:ON IndentationCheck"/>