[chore] remove some ut temp files and add some file to .gitignore (#8309)

fe/fe-core/src/test/java/org/apache/doris/alter/SchemaChangeJobV2Test.java

@@ -392,6 +392,7 @@ public class SchemaChangeJobV2Test {
         // prepare file
         File file = new File(fileName);
         file.createNewFile();
+        file.deleteOnExit();
         DataOutputStream out = new DataOutputStream(new FileOutputStream(file));
 
         SchemaChangeJobV2 schemaChangeJobV2 = new SchemaChangeJobV2(1, 1,1, "test",600000);

fe/fe-core/src/test/java/org/apache/doris/catalog/DiskInfoTest.java

@@ -56,6 +56,7 @@ public class DiskInfoTest {
         // write disk info to file
         File file = new File("./diskInfoTest");
         file.createNewFile();
+        file.deleteOnExit();
         DataOutputStream dos = new DataOutputStream(new FileOutputStream(file));
 
         DiskInfo diskInfo1 = new DiskInfo("/disk1");

fe/fe-core/src/test/java/org/apache/doris/persist/AlterRoutineLoadOperationLogTest.java

@@ -43,6 +43,7 @@ public class AlterRoutineLoadOperationLogTest {
         // 1. Write objects to file
         File file = new File(fileName);
         file.createNewFile();
+        file.deleteOnExit();
         DataOutputStream out = new DataOutputStream(new FileOutputStream(file));
 
         long jobId = 1000;