Merge transactions with same hash when writing to event db

[Sriep]

Fixes

Merge transactions with same hash when writing to event db

Changes

Need to be mentioned in CHANGELOG.md?

Tests

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• blobber:
• gosdk:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...

[dabasov]

lgtm

[codecov-commenter]

Codecov Report

Merging #2338 (29c3a17) into staging (afbbb96) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

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@@             Coverage Diff             @@
##           staging    #2338      +/-   ##
===========================================
- Coverage    28.97%   28.97%   -0.01%     
===========================================
  Files          377      377              
  Lines        63034    63034              
===========================================
- Hits         18267    18263       -4     
- Misses       42617    42626       +9     
+ Partials      2150     2145       -5     

Flag	Coverage Δ
Unit-Tests	28.97% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
.../0chain.net/smartcontract/dbs/event/transaction.go	4.81% <100.00%> (+2.40%)	⬆️

... and 4 files with indirect coverage changes

[peterlimg]

LGTM