Fix fallback creation with legacy style cluster

[vuil]

What this PR does / why we need it

When deem necessary to create cluster using legacy approach, said creation should work.
Also:

• added integration tests to verify that the cluster creation works under such scenario.

Which issue(s) this PR fixes

Fixes #2830

Describe testing done for PR

See provided integration tests

Release note

package-based-lcm: when feature flag is set, legacy style cluster creation should still work

PR Checklist

• x Squash the commits into one or a small number of logical commits
  
• x Use good commit messages
• x Ensure PR contains terms all contributors can understand and links all contributors can access

Additional information

Special notes for your reviewer

Tests had to work around an issue #2891
by prepopulating a tkr bom config map. Said workaround should be removed as soon as the issue is fixed.

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/2898/20220711154346/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/2898/20220711161309/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/2898/20220711221050/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[codecov]

Codecov Report

Merging #2898 (9f86a30) into main (447cacf) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2898      +/-   ##
==========================================
+ Coverage   43.83%   43.87%   +0.03%     
==========================================
  Files         414      414              
  Lines       41305    41316      +11     
==========================================
+ Hits        18105    18126      +21     
+ Misses      21507    21499       -8     
+ Partials     1693     1691       -2     

Impacted Files	Coverage Δ
...ons/controllers/packageinstallstatus_controller.go	80.64% <0.00%> (-2.16%)	⬇️
pkg/v1/tkg/client/get_cluster.go	54.16% <0.00%> (ø)
addons/controllers/clusterbootstrap_controller.go	63.54% <0.00%> (+0.26%)	⬆️
cmd/cli/plugin/tkr/v1alpha3/os.go	74.35% <0.00%> (+0.85%)	⬆️
pkg/v1/tkg/tkgctl/get_cluster.go	86.66% <0.00%> (+7.71%)	⬆️
...oller-manager/controllers/v3_cascade_controller.go	73.33% <0.00%> (+11.42%)	⬆️

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[anujc25]

Looks good.
Just one minor question.