Change PAX Plugin to Be Disabled by Default

[tuhaihe]

Currently, the PAX is enabled by default in configure, and users need to explicitly disable it via --disable-pax option. However, this behavior is inconsistent with most of the other extensions under the contrib/ or gpcontrib/ dir, which are typically disabled by default unless explicitly enabled.

PAX currently requires downloading several submodules during the build, for users without prior knowledge, this will lead to build failures.

This PR is to change the default behavior of PAX to disabled, which will be more user-friendly for users.

See: https://lists.apache.org/thread/q1n7hztzzydk1owhn73tc1b4chyhzx85

Fixes #ISSUE_Number

What does this PR do?

Type of Change

• [ ] Bug fix (non-breaking change)
• [ ] New feature (non-breaking change)
• [ ] Breaking change (fix or feature with breaking changes)
• [ ] Documentation update

Breaking Changes

Test Plan

• [ ] Unit tests added/updated
• [ ] Integration tests added/updated
• [ ] Passed make installcheck
• [ ] Passed make -C src/test installcheck-cbdb-parallel

Impact

Performance:

User-facing changes:

Dependencies:

Checklist

• [ ] Followed contribution guide
• [ ] Added/updated documentation
• [ ] Reviewed code for security implications
• [ ] Requested review from cloudberry committers

Additional Context

CI Skip Instructions

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[tuhaihe]

This PR relies on the https://github.com/apache/cloudberry-devops-release/pull/19

[gfphoenix78]

The file configure is generated by autoconf with version 2.69

[tuhaihe]

The file configure is generated by autoconf with version 2.69

Yes, it does, generated by autoconf 2.69.

[tuhaihe]

Hey everyone, I'm looking forward to your review and approval for this PR again. The base PR https://github.com/apache/cloudberry-devops-release/pull/19 has been merged, and the PAX-related tests have now passed. Thanks! @jiaqizho @gfphoenix78 @gongxun0928 @edespino