[Backport 6.2] fix(update-db-packages): stop only updated nodes

[mergify]

When updating multiple nodes db packages, SCT stops all the nodes. This is wrong and causes tests to fail when providing update_db_packages param.

Fix by removing broken logic and dropping code for nodes stop ordering.

fixes: #8551

Testing

• [ ]

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 relevant to this change (if needed)

(cherry picked from commit c140e7b)

Parent PR: #8857