Refactor default metrics

Complete refactor of the metrics. We ripped out the wallet specific metrics and included some basis blockchain and network metrics

# HELP bitcoin_best_block_index The block height or index
# TYPE bitcoin_best_block_index gauge
bitcoin_best_block_index 1500

# HELP bitcoin_best_block_timestamp_seconds The block time in seconds since epoch (Jan 1 1970 GMT)
# TYPE bitcoin_best_block_timestamp_seconds gauge
bitcoin_best_block_timestamp_seconds 1631697628

# HELP bitcoin_chain_header The block header value downloaded before new blocks or IBD
# TYPE bitcoin_chain_header gauge
bitcoin_chain_header 1500

# HELP bitcoin_chain_block The block height from getblockchaininfo
# TYPE bitcoin_chain_block gauge
bitcoin_chain_block 1500

# HELP bitcoin_chain_difficulty The proof-of-work difficulty as a multiple of the minimum difficulty
# TYPE bitcoin_chain_difficulty gauge
bitcoin_chain_difficulty 4.656542373906925e-10

# HELP bitcoin_connections_in Number of peers
# TYPE bitcoin_connections_in gauge
bitcoin_connections_in 1

# HELP bitcoin_connections_out Number of peers
# TYPE bitcoin_connections_out gauge
bitcoin_connections_out 0