Remove obsolete git checkout args

Git plugin 4.6.0 removes the outdated default arguments.  Their default
values were used in the tests previously.  No reason to show the default
values to users in tests or in example scripts.

Author: MarkEWaite

docs/scripted-pipelines.md

@@ -21,7 +21,7 @@ This is an example of a pipeline script with a single pipeline job that does Pre
 
 ``` groovy
 node {
-   checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], doGenerateSubmoduleConfigurations: false, extensions: [pretestedIntegration(pretestedIntegration: squash(), integrationBranch: 'master', repoName: 'origin')], submoduleCfg: [], userRemoteConfigs: [[credentialsId: 'GitHub', url: 'https://github.com/Praqma/phlow-test.git']]])
+   checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], extensions: [pretestedIntegration(pretestedIntegration: squash(), integrationBranch: 'master', repoName: 'origin')], userRemoteConfigs: [[credentialsId: 'GitHub', url: 'https://github.com/Praqma/phlow-test.git']]])
    sh 'mvn install'
    pretestedIntegrationPublisher()
 }

src/test/java/org/jenkinsci/plugins/pretestedintegration/integration/scm/git/AccumulatedCommitStrategyIT.java

@@ -257,7 +257,7 @@ public void happyDayPipelineDeclarativeACCUMULATED() throws Exception {
                 "    stages {\n" +
                 "        stage(\"checkout\") {\n" +
                 "            steps {\n" +
-                "                checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], doGenerateSubmoduleConfigurations: false, extensions: [pretestedIntegration(gitIntegrationStrategy: accumulated(), integrationBranch: 'master', repoName: 'origin')], submoduleCfg: [], userRemoteConfigs: [[url: '%URL']]])\n" +
+                "                checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], extensions: [pretestedIntegration(gitIntegrationStrategy: accumulated(), integrationBranch: 'master', repoName: 'origin')], userRemoteConfigs: [[url: '%URL']]])\n" +
                 "            }\n" +
                 "        }\n" +
                 "        stage(\"publish\") {\n" +

src/test/java/org/jenkinsci/plugins/pretestedintegration/integration/scm/git/GHI98_SupportForCredentialsIT.java

@@ -43,7 +43,7 @@ public class GHI98_SupportForCredentialsIT {
     final String uName = System.getProperty("usernameForTest");
     final String repo = System.getProperty("repoForTest");
     final String pipelineScript = "node {\n" +
-        "    checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], doGenerateSubmoduleConfigurations: false, extensions: [pretestedIntegration(gitIntegrationStrategy: squash(), integrationBranch: 'master', repoName: 'origin')], submoduleCfg: [], userRemoteConfigs: [[credentialsId: 'pipCredentials', url: '%repoForTest']]])\n" +
+        "    checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], extensions: [pretestedIntegration(gitIntegrationStrategy: squash(), integrationBranch: 'master', repoName: 'origin')], userRemoteConfigs: [[credentialsId: 'pipCredentials', url: '%repoForTest']]])\n" +
         "    pretestedIntegrationPublisher()\n" +
         "    echo \"Ohoy we've got success!\"\n" +
         "}";
@@ -89,4 +89,4 @@ private void cloneTestRepositoryAndPrepareABranch() throws Exception {
         g.push().setPushAll().setCredentialsProvider(new UsernamePasswordCredentialsProvider(uName, pw)).call();
     }
 
-}
+}

src/test/java/org/jenkinsci/plugins/pretestedintegration/integration/scm/git/PipAsGitExtensionIT.java

@@ -106,9 +106,7 @@ public void pipelineScriptTest() throws Exception {
                 "node {",
                 "checkout([$class: 'GitSCM'," +
                         " branches: [[name: '*/ready/**']]," +
-                        " doGenerateSubmoduleConfigurations: false," +
                         " extensions: [pretestedIntegration(gitIntegrationStrategy: squash(), integrationBranch: 'master', repoName: 'origin')]," +
-                        " submoduleCfg: []," +
                         " userRemoteConfigs: [[url: '" + "file://" + repo.getDirectory().getAbsolutePath() + "']]])",
                 "pretestedIntegrationPublisher()",
                 "}"), "\n"), false);

src/test/java/org/jenkinsci/plugins/pretestedintegration/integration/scm/git/SquashCommitStrategyIT.java

@@ -60,7 +60,7 @@ public void happyDayPipelineDeclarativeSQUASH() throws Exception {
                 "    stages {\n" +
                 "        stage(\"checkout\") {\n" +
                 "            steps {\n" +
-                "                checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], doGenerateSubmoduleConfigurations: false, extensions: [pretestedIntegration(gitIntegrationStrategy: squash(), integrationBranch: 'master', repoName: 'origin')], submoduleCfg: [], userRemoteConfigs: [[url: '%URL']]])\n" +
+                "                checkout([$class: 'GitSCM', branches: [[name: '*/ready/**']], extensions: [pretestedIntegration(gitIntegrationStrategy: squash(), integrationBranch: 'master', repoName: 'origin')], userRemoteConfigs: [[url: '%URL']]])\n" +
                 "            }\n" +
                 "        }\n" +
                 "        stage(\"publish\") {\n" +