fix-1516

[unknowissue]

修复了 #1516
修改内容：从库、表、字段去重修改为字段去重
ps: 目前是按照列匹配和脱敏的，当users表配置脱敏，users2表没有脱敏时，相同字段会被一并脱敏
需要实现逐行脱敏么?效率会不会低呢?

[codecov]

Codecov Report

Merging #1550 (23a192d) into master (4d96ac6) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1550   +/-   ##
=======================================
  Coverage   76.84%   76.84%           
=======================================
  Files          91       91           
  Lines       14309    14309           
=======================================
  Hits        10996    10996           
  Misses       3313     3313           

Impacted Files	Coverage Δ
sql/utils/data_masking.py	90.15% <100.00%> (ø)

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