Add missing BigQuery connector configuration properties to documentation

[shunki-fujita]

Description

Close: #28495
Several BigQuery connector configuration properties are defined in the code but missing from the documentation

Release notes

(x) This is not user-visible or is docs only, and no release notes are required.

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[ebyhr]

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[Copilot]

Pull request overview

This PR adds documentation for five previously undocumented BigQuery connector configuration properties that were already implemented in the code but missing from the configuration properties table, as identified in issue #28495.

Changes:

• Documents bigquery.metadata.parallelism and bigquery.metadata-page-size in the metadata section of the configuration table
• Documents bigquery.job.label-name and bigquery.job.label-format after the query results cache entry
• Documents bigquery.projection-pushdown-enabled before bigquery.max-parallelism

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[Copilot]

The documentation for bigquery.job.label-format states that the value may consist of "letters, digits, underscores, commas, spaces, equal signs, and predefined values", but the actual validation regex in FormatInterpolator.java (line 64) is [\\w ,_\\-=], which also allows hyphens (-). The hyphen character is missing from the documentation's list of allowed characters.

Suggested change

	consist of letters, digits, underscores, commas, spaces, equal signs, and
	consist of letters, digits, underscores, hyphens, commas, spaces, equal signs, and