SOLR-16093: Tests: don't require IPv6 (#2484)

The Java VM/host, doesn't always support IPv6, our tests shouldn't require it.
security.policy: Removed 3 lines that were only for tests.
diff --git a/gradle/testing/randomization/policies/solr-tests.policy b/gradle/testing/randomization/policies/solr-tests.policy
index 0c0c260..9dba0b9 100644
--- a/gradle/testing/randomization/policies/solr-tests.policy
+++ b/gradle/testing/randomization/policies/solr-tests.policy
@@ -47,9 +47,9 @@
   permission java.net.SocketPermission "127.0.0.1:1024-", "accept,listen,connect,resolve";
   permission java.net.SocketPermission "[::1]:1024-", "accept,listen,connect,resolve";
   // "dead hosts", we try to keep it fast
-  permission java.net.SocketPermission "[::1]:4", "connect,resolve";
-  permission java.net.SocketPermission "[::1]:6", "connect,resolve";
-  permission java.net.SocketPermission "[::1]:8", "connect,resolve";
+  permission java.net.SocketPermission "127.0.0.1:4", "connect,resolve";
+  permission java.net.SocketPermission "127.0.0.1:6", "connect,resolve";
+  permission java.net.SocketPermission "127.0.0.1:8", "connect,resolve";
 
   // Basic permissions needed for Lucene to work:
   permission java.util.PropertyPermission "*", "read,write";
diff --git a/solr/server/etc/security.policy b/solr/server/etc/security.policy
index 1dd9db3..48242b2 100644
--- a/solr/server/etc/security.policy
+++ b/solr/server/etc/security.policy
@@ -54,10 +54,6 @@
   permission java.net.SocketPermission "localhost:1024-", "accept,listen,connect,resolve";
   permission java.net.SocketPermission "127.0.0.1:1024-", "accept,listen,connect,resolve";
   permission java.net.SocketPermission "[::1]:1024-", "accept,listen,connect,resolve";
-  // "dead hosts", we try to keep it fast
-  permission java.net.SocketPermission "[::1]:4", "connect,resolve";
-  permission java.net.SocketPermission "[::1]:6", "connect,resolve";
-  permission java.net.SocketPermission "[::1]:8", "connect,resolve";
 
   // Basic permissions needed for Lucene to work:
   permission java.util.PropertyPermission "*", "read,write";
diff --git a/solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java b/solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java
index 902192f..55ad194 100644
--- a/solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java
+++ b/solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java
@@ -366,19 +366,19 @@
    * a "dead" host, if you try to connect to it, it will likely fail fast please consider using
    * mocks and not real networking to simulate failure
    */
-  public static final String DEAD_HOST_1 = "[::1]:4";
+  public static final String DEAD_HOST_1 = "127.0.0.1:4";
 
   /**
    * a "dead" host, if you try to connect to it, it will likely fail fast please consider using
    * mocks and not real networking to simulate failure
    */
-  public static final String DEAD_HOST_2 = "[::1]:6";
+  public static final String DEAD_HOST_2 = "127.0.0.1:6";
 
   /**
    * a "dead" host, if you try to connect to it, it will likely fail fast please consider using
    * mocks and not real networking to simulate failure
    */
-  public static final String DEAD_HOST_3 = "[::1]:8";
+  public static final String DEAD_HOST_3 = "127.0.0.1:8";
 
   /**
    * Assumes that Mockito/Bytebuddy is available and can be used to mock classes (e.g., fails if