feat(pbs): add retry limit for validator registration (#316)

[bhakiyakalimuthu]

📝 Description

This PR resolves #316 by introducing a configurable retry limit for validator registration requests. The goal is to prevent unnecessary network traffic, reduce load on relays, and avoid log clutter caused by excessive retries on client-side errors (e.g., 400, 429).

💡 Motivation and Context

if a relay responded with errors like 400 (unknown validator) or 429 (too many requests), client would keep retrying continously. This PR adds a limit to those retries to avoid putting unnecessary load on relays and to keep the logs clean.

What is Included

• Introduced register_validator_retry_limit to PbsConfig (default = 3)
• Used this field in send_register_validator_with_timeout to cap total attempts
• Updated retry logic to perform: max retry < retry_limit
• Ensured retry count is passed and logged in each attempt
• Maintained existing structure and logging patterns
• Added test to verify both 429 and 500 error cases

Behavior

• With register_validator_retry_limit = 3:
• Total of 3 request attempts allowed: retry = 0, 1, 2
• On retry = 3, aborts with logged error

Issue
Closes #316

[ltitanb]

Looks great, thanks for the PR! Left a small suggestion + lint check failed

[ltitanb]

looks great, thanks for the PR!