fix(approval-service): Fall back to manual strategy when there is no result available (#6012)

[bacherfl]

Closes #6012

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Merging #6017 (28b8aff) into master (9c90145) will decrease coverage by 0.98%.
The diff coverage is 91.66%.

@@            Coverage Diff             @@
##           master    #6017      +/-   ##
==========================================
- Coverage   54.26%   53.28%   -0.99%     
==========================================
  Files         399      327      -72     
  Lines       23460    22302    -1158     
  Branches     1204     1058     -146     
==========================================
- Hits        12731    11884     -847     
+ Misses       9816     9523     -293     
+ Partials      913      895      -18     

Impacted Files	Coverage Δ
...ce/pkg/handler/approval_triggered_event_handler.go	73.86% <91.66%> (+1.86%)	⬆️
...s/ktb-sequence-view/ktb-sequence-view.component.ts	30.32% <0.00%> (-29.02%)	⬇️
bridge/client/app/_utils/form.utils.ts	63.63% <0.00%> (-27.28%)	⬇️
...ient/app/_interceptors/http-loading-interceptor.ts	81.81% <0.00%> (-18.19%)	⬇️
bridge/shared/models/trace.ts	73.33% <0.00%> (-12.39%)	⬇️
bridge/client/app/_models/trace.ts	55.66% <0.00%> (-6.49%)	⬇️
bridge/client/app/_services/data.service.ts	22.38% <0.00%> (-6.29%)	⬇️
...project-settings/ktb-project-settings.component.ts	71.18% <0.00%> (-5.09%)	⬇️
...uation-details/ktb-evaluation-details.component.ts	17.81% <0.00%> (-4.85%)	⬇️
...lient/app/project-board/project-board.component.ts	68.83% <0.00%> (-4.80%)	⬇️
... and 81 more

[github-actions]

Docker Build Report

• Pushed keptn/approval-service:0.10.1-dev-PR-6017.202111170741 and keptn/approval-service:0.10.1-dev-PR-6017 (Source: approval-service/)