chore(tests/falcoctl): updated tests to latest main output.

[FedeDP]

Latest main output is a bit different:

2023-11-28 09:42:13 INFO  Resolving dependencies ... 
2023-11-28 09:42:14 INFO  Installing artifacts
                      └ refs: [ghcr.io/falcosecurity/plugins/plugin/dummy:latest]
2023-11-28 09:42:14 INFO  Preparing to pull artifact
                      └ ref: ghcr.io/falcosecurity/plugins/plugin/dummy:latest
2023-11-28 09:42:14 INFO  Pulling layer ff06a0d6ed4f 
2023-11-28 09:42:14 INFO  Pulling layer 1adcd4b01f59
2023-11-28 09:42:14 INFO  Pulling layer 5b7f12491641 
2023-11-28 09:42:14 INFO  Extracting and installing artifact
                      ├ type: plugin
                      └ file: dummy-0.9.1-linux-x86_64.tar.gz
2023-11-28 09:42:14 INFO  Artifact successfully installed
                      ├ name: ghcr.io/falcosecurity/plugins/plugin/dummy:latest
                      ├ type: plugin
                      ├ digest: sha256:5b7f1249164115be3b51f226d931230ef129c3e54143b30be2b07c59a034f46b
                      └ directory: /tmp/falcosecurity-testing-workdir-264431649/plugins\n

Ensure compatibility with newer output while retaining backward compatibility (only searching for Artifact successfully installed string).

[FedeDP]

This should help fixing a couple of test failing in falcosecurity/falco#2905

[poiana]

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This pull-request has been approved by: FedeDP, jasondellaluce

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