feat: Remove unused API Gateway resources and add multisearch parameter

[jrhoads]

Purpose

This PR removes unused API Gateway resources and configurations related to v2 and root proxy endpoints, along with adding support for the multisearch query string parameter to the organizations endpoints.

Approach

The changes involve deleting resources that are no longer in use and adding a new query string parameter to existing configurations.

Key Modifications

• Removal of unused resources: The v2/{proxy+} and /{proxy+} resources, along with their associated methods, integrations, method responses, and integration responses, have been removed. This declutters the API Gateway configuration.
• Addition of multisearch parameter: The multisearch query string parameter has been added to the organizations_any_staging and v2_organizations_any_staging methods and integrations. This allows for enhanced search capabilities.

Important Technical Details

• The removal of the proxy resources simplifies the API gateway definition and reduces potential confusion or misconfiguration.
• The addition of the multisearch parameter to the organizations endpoints is a minor functional enhancement.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

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