Changes

• add metrics NumberOfGetBlobsSuccesses and NumberOfGetBlobsFailures
  A successful response to engine_getBlobsV1 may include some (or even all) null values, indicating that the requested blobs are not available. We already track metrics for the number of blobs requested and the number of blobs sent, and based on that, we estimate the return rate on mainnet to be around 85%. For now, partial responses (some blobs returned, some nulls) are useful for the CL.
  However, after Fusaka's PeerDAS, partial responses will no longer be useful - CL will require either all requested blobs or none. This PR introduces new metrics to track fully successful responses (where all requested blobs are returned) versus successful but incomplete responses (where some blobs are missing). These metrics will help us estimate the rate of fully successful responses, which are critical for PeerDAS.
  These metrics are already included in the PeerDAS branch, but we also want to start collecting data from mainnet.

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No