Move settings initialization after module init phase (#3438)

### What problem does this PR solve?

1. Module init won't connect database any more.
2. Config in settings need to be used with settings.CONFIG_NAME

### Type of change

- [x] Refactoring

Signed-off-by: jinhai <haijin.chn@gmail.com>

deepdoc/parser/pdf_parser.py

@@ -24,7 +24,7 @@ import numpy as np
 from timeit import default_timer as timer
 from pypdf import PdfReader as pdf2_read
 
-from api.settings import LIGHTEN
+from api import settings
 from api.utils.file_utils import get_project_base_directory
 from deepdoc.vision import OCR, Recognizer, LayoutRecognizer, TableStructureRecognizer
 from rag.nlp import rag_tokenizer
@@ -41,7 +41,7 @@ class RAGFlowPdfParser:
         self.tbl_det = TableStructureRecognizer()
 
         self.updown_cnt_mdl = xgb.Booster()
-        if not LIGHTEN:
+        if not settings.LIGHTEN:
             try:
                 import torch
                 if torch.cuda.is_available():