[Backport 2023.1] feature(nemesis): introduce lock for target selection

[mergify]

since we run into multiple cases on parallel nemesis that there were multiple nemesis using the same node

we are introducing a lock over the selection of target nodes so we won't be able to pick it multiple times

Fixes: #6553

Testing

• parallel nemesis case with enterprise build - https://jenkins.scylladb.com/view/staging/job/scylla-staging/job/fruch/job/longevity-2TB-48h-authorization-and-tls-ssl-1dis-2nondis-nemesis-test/4/ https://argus.scylladb.com/test/eedcde34-5d24-4c94-84d7-07608f49b9da/runs?additionalRuns[]=af0022c1-586b-4556-989f-f6aec800f2b2
• provision tests

PR pre-checks (self review)

• I added the relevant backport labels
• I didn't leave commented-out/debugging code

Reminders

• Add New configuration option and document them (in sdcm/sct_config.py)
• Add unit tests to cover my changes (under unit-test/ folder)
• Update the Readme/doc folder relevent to this change (if needed)

(cherry picked from commit 2a551db )

Parent PR: #7016