develop to beta - fix legacy containers

[dmytrotkk]

This pull request introduces a new utility function, rm_legacy_containers, to remove legacy Docker containers with names matching the skale_ prefix. The function is integrated into various node update and shutdown operations to ensure old containers are properly cleaned up. Comprehensive tests are also added to verify the removal logic.

Container cleanup improvements:

• Added the rm_legacy_containers function in docker_utils.py, which removes all containers with names matching the skale_ prefix.
• Integrated rm_legacy_containers into the update and shutdown flows for both SKALE and FAIR nodes in base.py and fair.py, ensuring legacy containers are removed during these operations. [1] [2] [3] [4] [5]

Testing enhancements:

• Added rm_legacy_containers to the test imports and implemented test_rm_legacy_containers to verify that legacy containers are properly removed. [1] [2]
• Added a real Docker test for get_all_skaled_containers to validate container discovery logic.

Code organization:

• Updated import statements in base.py and fair.py to include the new utility. [1] [2]