fix: don't ban a peer for sending a banned peer

[stringhandler]

Description

Removes a check that would ban a peer if they sent a peer that we have banned.

Motivation and Context

The check would ban the source peer during peer sync if they sent a peer to us that we have banned. This is IMO exploitable, since a peer may not have connected to the banned peer in question and thus not know if it should be banned or not.

You could also get a peer banned in this manner:

1. As an evil peer, I connect to a target node A.
2. I then connect to a number of other nodes and get myself banned.
3. The nodes I connect to then will ban node A when they send my node address during sync

How Has This Been Tested?

CI

What process can a PR reviewer use to test or verify this change?

Not sure it's quite a mission to replicate this.

Breaking Changes

• None
• Requires data directory on base node to be deleted
• Requires hard fork
• Other - Please specify

[github-actions]

Test Results (CI)

1 222 tests   1 222 ✔️  9m 51s ⏱️
     39 suites         0 💤
       1 files           0 ❌

Results for commit 619949a.

[sdbondi]

Nice - so this was handled correctly discovery response but not in peer sync, think makes sense that the peer validator doesn't care that the peer is banned and that even a banned peer can have its peer record updated (as long as it stays banned)

[github-actions]

Test Results (Integration tests)

33 tests   33 ✔️  13m 46s ⏱️
11 suites    0 💤
  2 files      0 ❌

Results for commit 619949a.