Backport 5c6a923 from #3045.

What does this PR do?

Enables CNM/USM direct send if agent version is >= 7.81.0

Motivation

Enabling direct send at the operator level first.

Additional Notes

• Fixes environment variable not being set on process-agent container when Direct Send is disabled.
• 7.81.0 is not yet released, but this is the first agent version that can support Direct Send regardless of node kernel version.

Minimum Agent Versions

• Agent: v7.81.0
• Cluster Agent: n/a

Describe your test plan

• Add agent.datadoghq.com/cnm-direct-send-enabled=true annotation

  • With <7.80 ensure CNM direct send is NOT enabled:
    • DD_NETWORK_CONFIG_DIRECT_SEND=false
    • direct sender started log should NOT be present in system-probe logs.
    • process-agent container should be present
  • With 7.81+ ensure CNM direct is enabled:
    • DD_NETWORK_CONFIG_DIRECT_SEND=true
    • direct sender started log should be present in system-probe logs.
    • process-agent container should NOT be present

• Set agent.datadoghq.com/cnm-direct-send-enabled=false annotation

  • With any agent version:
    • DD_NETWORK_CONFIG_DIRECT_SEND=false
    • direct sender started log should NOT be present in system-probe logs.
    • process-agent container should be present

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label
• All commits are signed (see: signing commits)