Update fake driver for new initiator type field

[joseph-v]

What this PR does / why we need it: Update fake driver for new initiator type field

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[bot]]

Codecov Report

Merging #823 (c067e90) into master (ce1080e) will decrease coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #823      +/-   ##
==========================================
- Coverage   70.60%   70.58%   -0.02%     
==========================================
  Files         180      180              
  Lines       18652    18656       +4     
  Branches     2750     2750              
==========================================
  Hits        13169    13169              
- Misses       4644     4645       +1     
- Partials      839      842       +3     

Impacted Files	Coverage Δ
delfin/drivers/fake_storage/__init__.py	94.45% <100.00%> (-0.97%)	:arrow_down: