Change default database from mysql to pg (#7190)

dolphinscheduler-server/src/main/resources/config/install_config.conf

@@ -76,10 +76,11 @@ apiServerPort="12345"
 # ---------------------------------------------------------
 # The type for the metadata database
 # Supported values: ``postgresql``, ``mysql``.
-DATABASE_TYPE="mysql"
+DATABASE_TYPE="postgresql"
 
-# Spring datasource url, following <HOST>:<PORT>/<database>?<parameter> format
-SPRING_DATASOURCE_URL="jdbc:mysql://127.0.0.1:3306/dolphinscheduler?useUnicode=true&characterEncoding=UTF-8"
+# Spring datasource url, following <HOST>:<PORT>/<database>?<parameter> format, If you using mysql, you could use jdbc
+# string jdbc:mysql://127.0.0.1:3306/dolphinscheduler?useUnicode=true&characterEncoding=UTF-8 as example
+SPRING_DATASOURCE_URL="jdbc:postgresql://127.0.0.1:5432/dolphinscheduler"
 
 # Spring datasource username
 SPRING_DATASOURCE_USERNAME="ds_user"