[INLONG-823] Fix Database Tips for standalone deployment mode

[liaosunny123]

Prepare a Pull Request

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• Title Example: [INLONG-XYZ][Component] Title of the pull request

(The following XYZ should be replaced by the actual GitHub Issue number)

• Fixes [Improve] Delete deployment instruction about postgresql #823

Motivation

Delete PostgreSQL, which is not support in inlong start script.

Modifications

Delete PostgreSQL tips.

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.

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

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This change added tests and can be verified as follows:

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

Documentation

• Does this pull request introduce a new feature? (yes / no)
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[dockerzhang]

MySQL is not the only choice, and we can not only limit users to using MySQL.

[liaosunny123]

MySQL is not the only choice, and we can not only limit users to using MySQL.

The Tubemq start script use MYSQL as database ctl hard-codely. The other choice is that changing the run script to identify different database config.