Update skipped tests

[sp1999]

Description of changes:

Commit 1 This commit removes non-existent tests from the SKIPPED_TESTS file. This is because those tests had been removed previously for various reasons. #5799 removed external etcd tests for tinkerbell as external etcd was not supported at the time for kubernetes version v1.27. #7310 removed bottlerocket tests for tinkerbell as bottlerocket is being deprecated for baremetal which included the workload cluster upgrade tests. #7659 temporarily skipped couple of E2E tests which were broken either due to feature changes or env issues which included the TestTinkerbellAirgappedKubernetes129UbuntuProxyConfigFlow test but the latest v1.30 test for this flow has been passing for a while now so it's safe to remove from the SKIPPED_TESTS.

Commit 2 This commit adds more simple flow and upgrade flow tinkerbell tests for kubernetes versions v1.28 and v1.29 to SKIPPED_TESTS as we already skip the tests for those tests for kubernetes versions v1.26 and v1.27. Those tests are passing on the latest kubernetes version v1.30 so it's safe to skip the tests for older versions.

Commit 3 This commit adds v1.31 UpgradeFromLatest tests to SKIPPED_TESTS and updates the outdated tests to the latest kubernetes version v1.30 as these tests won't pass until the new EKS-A release is out with the new kubernetes version.

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 73.53%. Comparing base (7053c7e) to head (8346002). Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8643   +/-   ##
=======================================
  Coverage   73.53%   73.53%           
=======================================
  Files         578      578           
  Lines       36557    36557           
=======================================
  Hits        26882    26882           
  Misses       7955     7955           
  Partials     1720     1720           

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[sp1999]

/approve

[eks-distro-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: abhay-krishna, sp1999

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