issue: 3854806 Fixing TX buffers return order in TCP socket destruction

[AlexanderGrissik]

Description

When TCP socket is destroyed it frees the preallocated buffers after dst_entry is deleted. This returns the buffers to the global pool directly and breaks m_tx_num_bufs,m_zc_num_bufs ring counters.

What

1. Move the preallocated buffers cleanup before dst_entry destruction.
2. Add ring stats for m_tx_num_bufs and m_zc_num_bufs.

Why ?

Functionality

Change type

What kind of change does this PR introduce?

• [X] Bugfix
• [ ] Feature
• [ ] Code style update
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation content changes
• [ ] Tests
• [ ] Other

Check list

• [ ] Code follows the style de facto guidelines of this project
• [ ] Comments have been inserted in hard to understand places
• [ ] Documentation has been updated (if necessary)
• [ ] Test has been added (if possible)

[galnoam]

@AlexanderGrissik , move to fixed.