[Transaction] Transaction buffer metrics.

[congbobo184]

Motivation

Transaction buffer metrics add.

implement

    /** The active transactions. */
    public long activeTransactions;

    /** The commit transaction count of this transaction buffer. */
    public long commitTransactionCount;

    /** The abort transaction count of this transaction buffer. */
    public long abortTransactionCount;

    /** The registered transaction count of this transaction buffer. */
    public long registeredTransactionCount;

    /** The public transaction message count of this transaction buffer. */
    public long publishTxnMessageCount;

    /** The existed abort transactions of this transaction buffer. */
    public long existedAbortTransactions;

This is transaction buffer metrics.

Verifying this change

Add the tests for it

Does this pull request potentially affect one of the following parts:
If yes was chosen, please highlight the changes

Dependencies (does it add or upgrade a dependency): (no)
The public API: (no)
The schema: (no)
The default values of configurations: (no)
The wire protocol: (no)
The rest endpoints: (no)
The admin cli options: (no)
Anything that affects deployment: (no)

[congbobo184]

Transaction buffer don't need metrics, so close this PR.