[FEAT] Agent send metric improvement

[GabrielMCardozo]

Description

• Add the use of request.session for connection reuse
• Add send metric performance log (total requests, max queue size, avg send latency)
• Add requests mock dependency
• Fix iniconfig dependency
• Add a performance test for collecting and sending metrics
• Reduce thread sleep time between sending metrics batch

Checklist

• The commit message follows our guidelines
• Tests for the respective changes have been added
• The labels and/or milestones were added

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