Print warning & keep a count for prometheus when tikv raft size is exceeded

[matthewdarwin]

When defining an adapter for tikv, you can pass parameters like:

compression=zstd&compression_size_threshold=512000&batch_size_threshold=6000000

dfuse sometimes tries to insert data larger than the size_threshold because based on current design cannot split it into smaller chunks. If the size exceeds the tikv raft-entry-max-size parameter, then the entire insert fails. In case of insertion failure, dfuse should abort.

However, if dfuse does not abort, then a counter should be incremented and exposed to prometheus. Also log a message to the log file.