Docs Cleanup: Service-Level Overviews

## Context

At one point we switched our service-level overview files from including multiple tables (one table for client packages and one table for mgmt packages) to including one table which shows both client and management packages.

Since our service-level overview automation doesn't overwrite existing content in service-level overview pages, there are some service-level overview pages that still include the old, un-updated management-specific or client-specific tables instead of the full content of the tables.

## What to do
To fix this, the service-level overview pages should be updated to include the `-index.md` file instead of the `-mgmt-index.md` or `-client-index.md` file. See this PR: https://github.com/MicrosoftDocs/azure-docs-sdk-python/pull/1742/files

This will need to be done in:

* For each doc repo
* Remove `-mgmt-index.md` files
* Remove `-client-index.md` files
* Update tables in service-level overview markdown files to use the correct heading and table include (e.g. `## Packages - latest` heading and `[!INCLUDE [packages](load-testing-index.md)]` include)

This should be a one-time maintenance task.

Start by reviewing the linked PR to understand the intended service-level overview format and identify the affected doc repositories. In each repository, remove -mgmt-index.md and -client-index.md files and update service-level overview markdown to use the -index.md include with the correct heading and combined table. Done means no outdated management-specific or client-specific tables remain.

Written by the indexing model from the issue text.