Remove "redundant import" checkstyle suppression

Remove the "redundant import" checkstyle suppression since running
"organize imports" has fixed any violations.

Issue gh-8945

Author: philwebb

etc/checkstyle/checkstyle-suppressions.xml

@@ -3,7 +3,6 @@
 		"-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
 		"https://checkstyle.org/dtds/suppressions_1_2.dtd">
 <suppressions>
-	<suppress files=".*" checks="RedundantImport" />
 	<suppress files=".*" checks="RegexpSinglelineJava" />
 	<suppress files=".*" checks="SimplifyBooleanExpression" />
 	<suppress files=".*" checks="SimplifyBooleanReturn" />