Pure Modify alert and storage

[zhilong-xu]

What this PR does / why we need it:

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Release note:

[codecov]

Codecov Report

Merging #319 (d32286b) into pure (d09a9dc) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             pure     #319      +/-   ##
==========================================
+ Coverage   70.64%   70.65%   +0.01%     
==========================================
  Files         166      166              
  Lines       16138    16145       +7     
  Branches     1992     1992              
==========================================
+ Hits        11401    11408       +7     
  Misses       4057     4057              
  Partials      680      680              

Impacted Files	Coverage Δ
delfin/drivers/pure/flasharray/consts.py	100.00% <100.00%> (ø)
delfin/drivers/pure/flasharray/pure_flasharray.py	85.20% <100.00%> (+0.42%)	⬆️
delfin/drivers/fake_storage/__init__.py	95.06% <0.00%> (ø)