fix(anta.tests): Fix BGP tests failures

[carl-baillargeon]

Description

peerTcpInfo key is not present in the BGP output if the session is not Established so we need to skip that check in the logic.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have run pre-commit for code linting and typing (pre-commit run)
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (tox -e testenv)

[codspeed-hq]

CodSpeed Performance Report

Merging #941 will not alter performance

_{Comparing carl-baillargeon:fix/verify_bgp_specific_peers (b3d3963) with main (433b7f2)}

Summary

✅ 8 untouched benchmarks

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
85.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud