[fix](mysqldb) Fix mysqldb upgrade (#25111)

If user has database with same name mysql, will introduce problem when doing checkpoint.

Solution:

Add check for this situation, if duplicate, exit and print log info to prevent damage of metadata;
Add fe config field: mysqldb_replace_name to make things correct if user already has mysql db.
Related pr: #23087 #22868

fe/fe-common/src/main/java/org/apache/doris/common/Config.java

@@ -2210,4 +2210,11 @@ public class Config extends ConfigBase {
             + "the default value is 4320, which is 3 days"})
     public static int arrow_flight_token_alive_time = 4320;
 
+    @ConfField(mutable = true, description = {
+            "Doris 为了兼用 mysql 周边工具生态，会内置一个名为 mysql 的数据库，如果该数据库与用户自建数据库冲突，"
+            + "请修改这个字段，为 doris 内置的 mysql database 更换一个名字",
+            "To ensure compatibility with the MySQL ecosystem, Doris includes a built-in database called mysql. "
+            + "If this database conflicts with a user's own database, please modify this field to replace "
+            + "the name of the Doris built-in MySQL database with a different name."})
+    public static String mysqldb_replace_name = "mysql";
 }