run job with uncommitted transaction - how to find the transaction? is it still active?
Non-committed transactions will be automatically rolled-back if the session is terminated.
You can easily test this by:
USE tempdb;

CREATE TABLE dbo.TestTran
(
    ID INT NOT NULL
        CONSTRAINT PK_TestTran
        PRIMARY KEY CLUSTERED
        IDENTITY(1,1)
);

BEGIN TRAN
INSERT INTO dbo.TestTran DEFAULT VALUES;
SELECT * FROM dbo.TestTran;

Results will show a row inserted into dbo.TestTran.
Now, disconnect and reconnect the session.
--disconnect and reconnect

USE tempdb;

SELECT * FROM dbo.TestTran;

The results from the above SELECT statement will return no results since the non-committed transaction was automatically rolled back when the session was disconnected.
This is a primary tenet of all ACID-compliant database management systems.

Atomicity
A transaction is a unit of work in which a series of operations occur between the BEGIN TRANSACTION and END TRANSACTION statements of an application. A transaction executes exactly once and is atomic — all the work is done or none of it is.

Once you disconnect the session (or it completes without a COMMIT TRAN), the transaction will rollback to ensure none of the work has been done since the BEGIN TRAN statement.