fix(ratios): ignore invalid and empty coingecko ids

[onyb]

Summary

Our CoinGecko API usage is through the roof, putting us at risk of service discontinuation unless we significantly reduce our requests. This PR aims to reduce Coingecko API usage.

The way clients query token prices using the Ratios service is as follows:

1. Collect the Coingecko IDs to fetch prices for
2. Split them in batches, and request the Ratios service for each batch (say, with size 25).
3. If any of the batched requests fail, the system falls back to fetching prices individually for each ID in the batch.

A batched request can fail for invalid/unknown Coingecko IDs in the request, but rejecting the entire batch for even a single such ID is sub-optimal. This PR ensures that such IDs are ignored and we return prices for the remaining valid Coingecko IDs in the request (if any).

Before

GET https://ratios.bsg.brave.com/v2/relative/provider/coingecko/ethereum,onyb/usd/live
{
  "message": "Error validating Error validating coin url parameter",
  "code": 400,
  "data": {
    "validationErrors": {
      "coinIDs": "invalid coin",
      "err": "failed validation: invalid coin:  is not valid"
    }
  }
}

After

GET http://localhost:8080/v2/relative/provider/coingecko/ethereum,onyb/usd/live
{
  "payload": {
    "ethereum": {
      "usd": 2079.02,
      "usd_timeframe_change": 0.06567674390347
    }
  },
  "lastUpdated": "2025-03-04T13:47:12.306728+05:30"
}

Type of Change

• Product feature
• Bug fix
• Performance improvement
• Refactor
• Other

Tested Environments

• Development
• Staging
• Production

Before Requesting Review

• Does your code build cleanly without any errors or warnings?
• Have you used auto closing keywords?
• Have you added tests for new functionality?
• Have validated query efficiency for new database queries?
• Have documented new functionality in README or in comments?
• Have you squashed all intermediate commits?
• Is there a clear title that explains what the PR does?
• Have you used intuitive function, variable and other naming?
• Have you requested security and/or privacy review if needed
• Have you performed a self review of this PR?

Manual Test Plan

Tested locally on my branch. Once deployed to staging, I'll test with a local build of brave-core.