[PLUGINS] Add parser unit tests for icmp_ping plugin

[utksh1]

Summary

The scan did not find a dedicated parser/plugin test file for icmp_ping. Add focused tests using sample output so parser behavior is protected.

Files found during scan

• plugins/icmp_ping/parser.py
• plugins/icmp_ping/metadata.json

Acceptance criteria

• Add a dedicated backend test or extend a clearly related parser suite for icmp_ping.
• Cover at least one normal output sample.
• Cover empty or malformed output without crashing.

[Rakshak05]

Hii @utksh1, I would like to work on this. Can you please assign it to me under GSSoC'26 contributor!?

[Rakshak05]

Hii @utksh1, i've raised a PR for this issue at #1526.
Please check it out!

[Rakshak05]

@utksh1 Could you please reopen the issue and assign me the issue first.