Fix/failed kad test

[yashksaini-coder]

What was wrong?

Fixes Issue #962 :

KAD-DHT tests became ~33% slower (from sub-1s to ~1.66s) after PR #892's security fix that changed bind address from 0.0.0.0 to 127.0.0.1—specifically affected the test_provide_and_find_providers test.

How was it fixed?

Implemented configurable bind addresses through LIBP2P_BIND environment variable while keeping 127.0.0.1 as secure default:

DEFAULT_BIND_ADDRESS = os.getenv("LIBP2P_BIND", "127.0.0.1")
LISTEN_MADDR = multiaddr.Multiaddr(f"/ip4/{DEFAULT_BIND_ADDRESS}/tcp/0")

This provides:

• Security by default (127.0.0.1)
• 33% faster tests when needed (0.0.0.0)
• Backward compatibility
• Comprehensive test coverage

To-Do

• Clean up commit history
• Add or update documentation related to these changes
• Add entry to the release notes

[yashksaini-coder]

@seetadev @acul71 Based on the recent issue addressed in the discussion #949 I've raised this PR, along with proper issue #962 and has updated implemented the fix as per given guidelines,

The applied suggestion lead to the results here

I would like to request a review on this PR, and also have a look at the #962 issue.

[seetadev]

@yashksaini-coder : Appreciate your great efforts. Will share feedback soon.