unity add rest retry time

[tanjiangyu-ghca]

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 #524 (b270169) into unity_1123 (98743cc) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@              Coverage Diff               @@
##           unity_1123     #524      +/-   ##
==============================================
- Coverage       70.62%   70.61%   -0.02%     
==============================================
  Files             180      180              
  Lines           18862    19037     +175     
  Branches         2802     2821      +19     
==============================================
+ Hits            13322    13443     +121     
- Misses           4674     4726      +52     
- Partials          866      868       +2     

Impacted Files	Coverage Δ
delfin/drivers/dell_emc/unity/rest_handler.py	46.48% <0.00%> (-0.51%)	⬇️
delfin/drivers/dell_emc/vmax/rest.py	42.02% <0.00%> (-2.17%)	⬇️
delfin/drivers/fake_storage/__init__.py	94.65% <0.00%> (-0.51%)	⬇️
delfin/drivers/driver.py	61.76% <0.00%> (ø)
delfin/common/constants.py	100.00% <0.00%> (ø)
delfin/drivers/dell_emc/vmax/vmax.py	83.33% <0.00%> (+2.77%)	⬆️
delfin/drivers/dell_emc/vmax/client.py	79.63% <0.00%> (+6.28%)	⬆️