Refactor the setting to make unit test easier (#22405)

Some bugs caused by less unit tests in fundamental packages. This PR
refactor `setting` package so that create a unit test will be easier
than before.

- All `LoadFromXXX` files has been splited as two functions, one is
`InitProviderFromXXX` and `LoadCommonSettings`. The first functions will
only include the code to create or new a ini file. The second function
will load common settings.
- It also renames all functions in setting from `newXXXService` to
`loadXXXSetting` or `loadXXXFrom` to make the function name less
confusing.
- Move `XORMLog` to `SQLLog` because it's a better name for that.

Maybe we should finally move these `loadXXXSetting` into the `XXXInit`
function? Any idea?

---------

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>

tests/integration/migration-test/migration_test.go

@@ -57,7 +57,7 @@ func initMigrationTest(t *testing.T) func() {
 		setting.CustomConf = giteaConf
 	}
 
-	setting.LoadForTest()
+	setting.InitProviderAndLoadCommonSettingsForTest()
 
 	assert.True(t, len(setting.RepoRootPath) != 0)
 	assert.NoError(t, util.RemoveAll(setting.RepoRootPath))
@@ -83,8 +83,8 @@ func initMigrationTest(t *testing.T) func() {
 	}
 
 	assert.NoError(t, git.InitFull(context.Background()))
-	setting.InitDBConfig()
-	setting.NewLogServices(true)
+	setting.LoadDBSetting()
+	setting.InitLogs(true)
 	return deferFn
 }
 
@@ -292,7 +292,7 @@ func doMigrationTest(t *testing.T, version string) {
 		return
 	}
 
-	setting.NewXORMLogService(false)
+	setting.InitSQLLog(false)
 
 	err := db.InitEngineWithMigration(context.Background(), wrappedMigrate)
 	assert.NoError(t, err)