PESDLC-1069 Disable decomission tests

[savex]

Some investigation results on the above error
This error here prevents cluster from be connected to the CloudV2 API

test_id:    rptest.redpanda_cloud_tests.high_throughput_test.HighThroughputTest.test_add_and_decommission
status:     FAIL
run time:   17 minutes 48.719 seconds
...
subprocess.CalledProcessError: Command '['tsh', 'ssh', '--proxy=proxy.tp.redpanda.com:443', '--auth=okta', '--identity=/tmp/machine-id/identity', 'redpanda@co53q695otfeo26a3q80-agent', 'sudo', 'systemctl', 'enable', '--now', 'redpanda-agent.service', 'redpanda-agent-boot.service', 'redpanda-agent-init.service']' returned non-zero exit status 1.

As a result, cloud can't be deleted and stays intact on the account. This is happening for at least a week. So the actual Clusters in the CDT account were not deleted at all. Piling up, spending money and doing nothing.
PR to fix this up:

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v23.3.x
• v23.2.x

Release Notes

• none