testsys: change clustersharedSg to clusterSg in templated var

[etungsten]

Issue #, if available:
N/A

Description of changes:
In the EC2 karpenter instance resource config, instead of using the cluster shared SG, which is now obsolete, use cluster SG.

Testing:

[cargo-make] INFO - Execute Command: "/home/fedora/bottlerocket/tools/twoliter/twoliter" "--log-level=info" "make" "test" "--project-path=/home/fedora/bottlerocket/Twoliter.toml" "--cargo-home=/home/fedora/bottlerocket/.cargo" "--"
[cargo-make][1] INFO - Build File: /tmp/.tmpSRwG0d/Makefile.toml
[cargo-make][1] INFO - Task: test
[cargo-make][1] INFO - Profile: development
[cargo-make][1] INFO - Running Task: test
[2023-09-19T20:33:58Z INFO  testsys::run] Successfully added 'bottlerocket'
[2023-09-19T20:33:58Z INFO  testsys::run] Successfully added 'bottlerocket-karpenter-vugp'
[2023-09-19T20:33:58Z INFO  testsys::run] Successfully added 'bottlerocket-karpenter'
[cargo-make][1] INFO - Build Done in 1.67 seconds.
[cargo-make] INFO - Build Done in 905.67 seconds.

...
$ cli  --kubeconfig testsys.kubeconfig status 
 NAME                    TYPE      STATE       PASSED   FAILED   SKIPPED 
 bottlerocket-karpente   Test      passed           5        0      7206 
 bottlerocket            Resourc   completed 

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[webern]

I kicked re-run of the failed actions. Looked like something weird, just said "Build Failed" with no logs.

[etungsten]

Need corresponding changes in testsys ec2 karpenter agent: bottlerocket-os/bottlerocket-test-system#874