Always run known hosts tests locally

No issues have been detected in local execution of the known hosts tests.
Don't reduce the detection opportunities in local development environments
or in environments that are not one of the ci.jenkins.io servers.

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

@@ -3,6 +3,7 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 import static org.jenkinsci.plugins.gitclient.verifier.KnownHostsTestUtil.nonGitHubHost;
+import static org.jenkinsci.plugins.gitclient.verifier.KnownHostsTestUtil.runKnownHostsTests;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
 
@@ -11,7 +12,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.time.Duration;
-import java.util.concurrent.ThreadLocalRandom;
 import org.awaitility.Awaitility;
 import org.junit.Assume;
 import org.junit.Before;
@@ -43,8 +43,7 @@ public void assignVerifiers() throws IOException {
 
     @Test
     public void connectWhenHostKeyNotInKnownHostsFileForOtherHostNameThenShouldFail() throws Exception {
-        // Only test 10% of the time to reduce load on ssh providers
-        Assume.assumeTrue(ThreadLocalRandom.current().nextInt(10) == 0);
+        Assume.assumeTrue(runKnownHostsTests());
         fakeKnownHosts = knownHostsTestUtil.createFakeKnownHosts("fake2.ssh", "known_hosts_fake2", FILE_CONTENT);
         KnownHostsFileVerifier knownHostsFileVerifier = spy(new KnownHostsFileVerifier());
         when(knownHostsFileVerifier.getKnownHostsFile()).thenReturn(fakeKnownHosts);

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

@@ -148,6 +148,19 @@ public static String nonGitHubHost() {
         return nonGitHubHosts[ThreadLocalRandom.current().nextInt(nonGitHubHosts.length)];
     }
 
+    private static final String JENKINS_URL =
+            System.getenv("JENKINS_URL") != null ? System.getenv("JENKINS_URL") : "http://localhost:8080/";
+
+    /* Return true if known hosts tests should be run in this context */
+    public static boolean runKnownHostsTests() {
+        if (!JENKINS_URL.contains("ci.jenkins.io")) {
+            /* Always run the tests if not on ci.jenkins.io */
+            return true;
+        }
+        // Only test 10% of the time on ci.jenkins.io to reduce load on ssh providers
+        return ThreadLocalRandom.current().nextInt(10) == 0;
+    }
+
     /* Always return false, retained for test compatibility */
     public static boolean isKubernetesCI() {
         return false;

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

@@ -3,6 +3,7 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 import static org.jenkinsci.plugins.gitclient.verifier.KnownHostsTestUtil.nonGitHubHost;
+import static org.jenkinsci.plugins.gitclient.verifier.KnownHostsTestUtil.runKnownHostsTests;
 
 import hudson.model.StreamBuildListener;
 import hudson.model.TaskListener;
@@ -13,7 +14,6 @@
 import java.nio.file.Path;
 import java.time.Duration;
 import java.util.Collections;
-import java.util.concurrent.ThreadLocalRandom;
 import org.awaitility.Awaitility;
 import org.junit.Assume;
 import org.junit.Before;
@@ -41,8 +41,7 @@ public void assignVerifier() { // For github.com
 
     @Test
     public void connectWhenHostKeyProvidedForOtherHostNameThenShouldFail() throws Exception {
-        // Only test 10% of the time to reduce load on ssh providers
-        Assume.assumeTrue(ThreadLocalRandom.current().nextInt(10) == 0);
+        Assume.assumeTrue(runKnownHostsTests());
         HostKeyVerifierFactory verifier = new ManuallyProvidedKeyVerifier(hostKey);
 
         KnownHostsTestUtil.connectToHost(