fix: unit test TestNewOperation. Fixes #7063

[tczhao]

Fixes #7063

tested with go test -count=100 -run=TestNewOperation ./server/event/dispatch

order of pipeline execution (list) may be different from the order of submission due to network delays

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[codecov]

Codecov Report

Merging #7069 (e176242) into master (18c953d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #7069   +/-   ##
=======================================
  Coverage   48.54%   48.54%           
=======================================
  Files         265      265           
  Lines       19307    19307           
=======================================
  Hits         9373     9373           
+ Misses       8880     8879    -1     
- Partials     1054     1055    +1     

Impacted Files	Coverage Δ
cmd/argoexec/commands/emissary.go	50.35% <0.00%> (-1.44%)	⬇️
workflow/metrics/server.go	19.29% <0.00%> (+3.50%)	⬆️

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