Don't always set the trail.Failed to true due to how SetValid works

[mstoykov]

No description provided.

[mstoykov]

A cautionary tale on RTFM ... https://pkg.go.dev/gopkg.in/guregu/null.v3#Bool.SetValid

[na--]

LGTM, though if possible, can you check this in some test?

[codecov-io]

Codecov Report

Merging #1907 (cb9d859) into master (f0169c0) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1907      +/-   ##
==========================================
- Coverage   71.21%   71.17%   -0.04%     
==========================================
  Files         183      183              
  Lines       14325    14337      +12     
==========================================
+ Hits        10202    10205       +3     
- Misses       3497     3504       +7     
- Partials      626      628       +2     

Flag	Coverage Δ
ubuntu	71.17% <100.00%> (+0.01%)	⬆️
windows	?

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

Impacted Files	Coverage Δ
lib/netext/httpext/transport.go	97.14% <100.00%> (ø)
js/common/initenv.go	86.66% <0.00%> (-13.34%)	⬇️
js/initcontext.go	90.10% <0.00%> (-2.20%)	⬇️
lib/executor/vu_handle.go	93.33% <0.00%> (-1.91%)	⬇️
core/engine.go	85.13% <0.00%> (-1.81%)	⬇️
js/runner.go	80.86% <0.00%> (-0.58%)	⬇️
js/modules/k6/http/http.go	100.00% <0.00%> (ø)
cmd/ui_windows.go
output/cloud/metrics_client.go	80.76% <0.00%> (ø)
output/cloud/output.go	81.28% <0.00%> (+0.65%)	⬆️
... and 2 more

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[na--]

LGTM, it might be simpler to also add the v0.31.1 release notes in this same PR

[imiric]

@na-- I'd leave the release notes for a separate PR.