feature: asynchronously update file statistics during vacuum

[gongxun0928]

Previously, statistics (min-max, sum, count, etc.) were computed synchronously during data insertion, causing significant slowdowns due to heavy computational overhead.

This change introduces an asynchronous approach to maintain statistics:

• Add a GUC parameter to control statistics collection during writes (disabled by default)
• Skip statistics computation during INSERT to ensure fast writes
• Update statistics asynchronously during VACUUM on PAX tables by scanning file metadata
• Re-read files and refresh statistics only when metadata indicates they are stale
• A vacuum was implemented. First, it queries the data block file marked for deletion, scans for valid tuples within it, and rewrites them to a new data file.

In this PR, you'll notice changes in many test results related to VACUUM. The main reason is that after data has been updated or deleted, when VACUUM is performed, files marked for deletion will be rewritten—potentially consolidating multiple such files in the process.

It's important to note that this PR does not include the implementation of VACUUM FULL.

create table t1(c1 int, c2 int, c3 int, c4 int, c5 int, c6 int) using pax with(minmax_columns='c1,c2,c3,c4,c5,c6');
set pax.enable_sync_collect_stats to on; -- collect stats synchronously
insert into t1 select i,i,i,i,i,i from generate_series(1,1000000) i;
INSERT 0 1000000
Time: 2733.731 ms (00:02.734)

create table t2(c1 int, c2 int, c3 int, c4 int, c5 int, c6 int) using pax;
insert into t2 select i,i,i,i,i,i from generate_series(1,1000000) i;
INSERT 0 1000000
Time: 1816.836 ms (00:01.817)

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

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