fix: drop the manager handler correctly

[gusinacio]

The current implementation implements the Drop trait for the manager by aborting the handler.

The manager was being dropped at the end of create_agent() and wouldn't execute the thread correctly. This PR transfer the ownership to the main function which is dropped correctly when the execution is terminated.

[github-actions]

Pull Request Test Coverage Report for Build 7201920144

• 0 of 12 (0.0%) changed or added relevant lines in 2 files are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 63.213%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tap-agent/src/agent.rs	0	3	0.0%
tap-agent/src/main.rs	0	9	0.0%

Files with Coverage Reduction	New Missed Lines	%
tap-agent/src/agent.rs	1	0.0%
tap-agent/src/tap/sender_allocation_relationships_manager.rs	2	68.02%

Totals
Change from base Build 7197062158:	-0.07%
Covered Lines:	2294
Relevant Lines:	3629

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💛 - Coveralls