Do not use deprecated log config options by default (#26592)

Simplify the log config

* Remove unnecessary `ROUTER` config, it defaults to the `MODE`.
* `XORM` config was deprecated

docker/root/etc/templates/app.ini

 [log]
 MODE = console
 LEVEL = info
-ROUTER = console
 ROOT_PATH = /data/gitea/log
 
 [security]

tests/mssql.ini.tmpl

 [log]
 MODE                 = {{TEST_LOGGER}}
 ROOT_PATH            = {{REPO_TEST_DIR}}mssql-log
-ROUTER               = ,
-XORM                 = file
 ENABLE_SSH_LOG       = true
+logger.xorm.MODE     = file
 
 [log.test]
 LEVEL                = Info

tests/mysql.ini.tmpl

 [log]
 MODE                 = {{TEST_LOGGER}}
 ROOT_PATH            = {{REPO_TEST_DIR}}mysql-log
-ROUTER               = ,
-XORM                 = file
 ENABLE_SSH_LOG       = true
+logger.xorm.MODE     = file
 
 [log.test]
 LEVEL                = Info

tests/mysql8.ini.tmpl

 [log]
 MODE                 = {{TEST_LOGGER}}
 ROOT_PATH            = {{REPO_TEST_DIR}}mysql8-log
-ROUTER               = ,
-XORM                 = file
 ENABLE_SSH_LOG       = true
+logger.xorm.MODE     = file
 
 [log.test]
 LEVEL                = Info

tests/pgsql.ini.tmpl

 [log]
 MODE                 = {{TEST_LOGGER}}
 ROOT_PATH            = {{REPO_TEST_DIR}}pgsql-log
-ROUTER               = ,
-XORM                 = file
 ENABLE_SSH_LOG       = true
+logger.xorm.MODE     = file
 
 [log.test]
 LEVEL                = Info

tests/sqlite.ini.tmpl

 [log]
 MODE                 = {{TEST_LOGGER}}
 ROOT_PATH            = {{REPO_TEST_DIR}}sqlite-log
-ROUTER               = ,
-XORM                 = file
 ENABLE_SSH_LOG       = true
+logger.xorm.MODE     = file
 
 [log.test]
 LEVEL                = Info