Resolve Pitest suppression for SingleSpaceSeparatorCheck

[Kevin222004]

Related to #7797

kill mutation

checkstyle/.ci/pitest-suppressions/pitest-whitespace-suppressions.xml

Lines 120 to 136 in fa68569

	<mutation unstable="false">
	<sourceFile>SingleSpaceSeparatorCheck.java</sourceFile>
	<mutatedClass>com.puppycrawl.tools.checkstyle.checks.whitespace.SingleSpaceSeparatorCheck</mutatedClass>
	<mutatedMethod>visitEachToken</mutatedMethod>
	<mutator>org.pitest.mutationtest.engine.gregor.mutators.NonVoidMethodCallMutator</mutator>
	<description>removed call to com/puppycrawl/tools/checkstyle/api/DetailAST::getParent</description>
	<lineContent>final DetailAST parent = node.getParent();</lineContent>
	</mutation>
	<mutation unstable="false">
	<sourceFile>SingleSpaceSeparatorCheck.java</sourceFile>
	<mutatedClass>com.puppycrawl.tools.checkstyle.checks.whitespace.SingleSpaceSeparatorCheck</mutatedClass>
	<mutatedMethod>visitEachToken</mutatedMethod>
	<mutator>org.pitest.mutationtest.engine.gregor.mutators.experimental.NakedReceiverMutator</mutator>
	<description>replaced call to com/puppycrawl/tools/checkstyle/api/DetailAST::getParent with receiver</description>
	<lineContent>final DetailAST parent = node.getParent();</lineContent>
	</mutation>

[Kevin222004]

I am working on it, send pr when its approved

[rnveach]

I am closing this and moving it under #12601.