JDBC Postgresql Error: transaction is aborted

**Describe the bug**
I'm using the JDBC driver to sink Postgresql, and when it gets an error from postgres, i'm not able to ingest more data because I get this Error: `current transaction is aborted, commands ignored until end of transaction block`

**To Reproduce**
Steps to reproduce the behavior:
1. Set JDBC Postgresql sink. I did this quickstart
https://pulsar.apache.org/docs/en/io-quickstart/#connect-pulsar-to-postgresql

2. I will send two messages to Pulsar topic from a Java Client and It has setted a schema definition
```
getProducer(eventTopic).newMessage(Schema.AVRO(Esquema.class))
.key("test")
.value(m)
.send();
```

3. The table of Postgres has a primary key. So It will get an error when It gets a duplicate key

```
CREATE TABLE test (
id integer PRIMARY KEY,
name text null
);
```

4. I sent two messages with the same primary key and i got this error, but It keeps on "Trasaction aborted" and i can't send new messages until I delete the sink

```
2022-01-25T13:22:49,236+0000 [pool-6-thread-1] ERROR org.apache.pulsar.io.jdbc.JdbcAbstractSink - Got exception
org.postgresql.util.PSQLException: ERROR: current transaction is aborted, commands ignored until end of transaction block
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2533) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2268) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:313) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:448) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:369) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:159) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgPreparedStatement.execute(PgPreparedStatement.java:148) ~[postgresql-42.2.12.jar:42.2.12]
at org.apache.pulsar.io.jdbc.JdbcAbstractSink.flush(JdbcAbstractSink.java:203) ~[pulsar-io-jdbc-core-2.9.1.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:829) [?:?]
Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "id_pkey"
Detail: Key (id)=(16377) already exists.
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2533) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2268) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:313) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:448) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:369) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:159) ~[postgresql-42.2.12.jar:42.2.12]
at org.postgresql.jdbc.PgPreparedStatement.execute(PgPreparedStatement.java:148) ~[postgresql-42.2.12.jar:42.2.12]
at org.apache.pulsar.io.jdbc.JdbcAbstractSink.flush(JdbcAbstractSink.java:203) ~[pulsar-io-jdbc-core-2.9.1.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) ~[?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[?:?]
... 3 more

```
All new messages that i send to topic, it will be ignored by this transaction block.

**Desktop (please complete the following information):**
- OS: Ubuntu 20.04
- Pulsar: 2.9.1
- Postgres: 12

Start with the failure location reported in JdbcAbstractSink.flush at line 203 and reproduce the PostgreSQL sink scenario using a duplicate primary key. Trace how the transaction is handled after the duplicate-key error, then verify that later messages can be processed without deleting or restarting the sink.

Written by the indexing model from the issue text.