[Improve][Zeta] Set the default slot-num value to twice the number of CPU cores

[Hisoka-X]

Purpose of this pull request

Set the default slot-num value to twice the number of CPU cores, make default values more useful.

Does this PR introduce any user-facing change?

Yes, but it is more useful than the default of 2 and does not affect existing jobs.

How was this patch tested?

add new test

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config

[Copilot]

Pull Request Overview

This pull request changes the default value for the slot-num configuration parameter from a fixed value of 2 to twice the number of CPU cores, making the default configuration more appropriate for different hardware environments.

• Updates the default slot-num value to be calculated dynamically based on CPU cores
• Adds comprehensive test coverage for the new default behavior
• Updates documentation to reflect the new default value calculation

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ServerConfigOptions.java	Changes default slot-num value from 2 to CPU cores * 2
YamlSeaTunnelConfigParserTest.java	Adds test to verify new default slot calculation behavior
customize-seatunnel.yaml	New test configuration file for slot service testing
customize-client.yaml	Fixes typo in cluster name from "custmoize" to "customize"
YamlSeaTunnelConfigLocator.java	Changes class visibility from final to non-final for testing
Documentation files	Updates English and Chinese docs to explain new default behavior

Comments suppressed due to low confidence (1)

seatunnel-engine/seatunnel-engine-common/src/test/java/org/apache/seatunnel/engine/common/config/YamlSeaTunnelConfigParserTest.java:123

• The error message should be more descriptive and professional. Consider using a more specific message like "Failed to locate customize-seatunnel.yaml configuration file in working directory or classpath".

            throw new RuntimeException("can't find yaml in resources");

[Copilot]

[nitpick] The static import is added at the top but used only in the new test method. Consider moving this import closer to where it's used or ensure it follows the project's import organization standards.