[Refactor] refactor duplicated code lines and fix typo errors

[gunli]

(If this PR fixes a github issue, please add Fixes #<xyz>.)

Fixes #

(or if this PR is one task of a github issue, please add Master Issue: #<xyz> to link to the master issue.)

Master Issue: #

Motivation

There are duplicated code lines and typo errors in producer_partition.go, fix them.

Modifications

Describe the modifications you've done.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicable / docs / GoDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation

[hezhangjian]

Overall looks good. But I don't think some rename is necessary. Like

• rename conn to connection
• rename flag to mark

[gunli]

It seems the CI is broken.

[shibd]

It seems the CI is broken.

The ci failed info:

topic="persistent://public/default/my-topic-651450217"
    transaction_test.go:284: 
        	Error Trace:	/pulsar/pulsar-client-go/pulsar/transaction_test.go:284
        	Error:      	The consumer should not receive uncommitted message
        	Test:       	TestConsumeAndProduceWithTxn

The root cause is you forget to set useTxn = true on here.

#1039 (comment)