fix delivery API without positionAmt bugs

[drinkthere]

add positionAmt in both account_service.go and account_servie_test.go

[codecov]

Codecov Report

Merging #354 (d76b9d5) into master (09e883c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #354   +/-   ##
=======================================
  Coverage   72.78%   72.78%           
=======================================
  Files          62       62           
  Lines        5868     5868           
=======================================
  Hits         4271     4271           
  Misses       1181     1181           
  Partials      416      416           

Impacted Files	Coverage Δ
v2/delivery/account_service.go	69.23% <ø> (ø)

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