Use rename in place of copy buffer

[Hitenjain14]

Changes

Fixes

Tests

Tasks to complete before merging PR:

• [ ] Ensure system tests are passing. If not Run them manually to check for any regressions :clipboard:
• [ ] 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):

• 0chain:
• gosdk:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...

[codecov-commenter]

Codecov Report

Merging #1298 (1819091) into sprint-1.11 (55f45ac) will increase coverage by 0.00%. The diff coverage is 90.90%.

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@@             Coverage Diff              @@
##           sprint-1.11    #1298   +/-   ##
============================================
  Coverage        23.81%   23.81%           
============================================
  Files               86       86           
  Lines            10021    10021           
============================================
+ Hits              2386     2387    +1     
  Misses            7337     7337           
+ Partials           298      297    -1     

Flag	Coverage Δ
Unit-Tests	23.81% <90.90%> (+<0.01%)	:arrow_up:

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

Files	Coverage Δ
...in.net/blobbercore/allocation/file_changer_base.go	46.51% <100.00%> (+1.27%)	:arrow_up:
...ode/go/0chain.net/blobbercore/filestore/storage.go	39.10% <100.00%> (+0.18%)	:arrow_up:
code/go/0chain.net/blobbercore/filestore/store.go	0.00% <ø> (ø)
...ain.net/blobbercore/handler/file_command_update.go	0.00% <0.00%> (ø)
...ain.net/blobbercore/handler/file_command_upload.go	13.40% <0.00%> (-0.08%)	:arrow_down:

[service-0chain]

Manual system tests [failure] with the following config	config	value
tests skipped	false
system-tests
gosdk	NOT OVERRIDDEN
zboxcli
zwalletcli
0chain
blobber	feat/rename-temp
authorizer
0box
0dns