Simplify formatting of known hosts file content

Author: MarkEWaite

src/test/java/org/jenkinsci/plugins/gitclient/verifier/KnownHostsFileVerifierTest.java

@@ -23,11 +23,7 @@
 public class KnownHostsFileVerifierTest {
 
     private static final String FILE_CONTENT =
-            """
-            github.com\
-             ecdsa-sha2-nistp256\
-             AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=\
-            """;
+            "github.com ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBEmKSENjQEezOmxkZMy7opKgwFB9nkt5YRrYMjNuG5N87uRgg6CLrbo5wAdT/y6v0mKV0U2w0WZ2YB/++Tpockg=";
 
     // Create a temporary folder and assert folder deletion at end of tests
     @Rule