Update references to "40+ Azure Services" to 50+

[joshfree]

nit: Azure MCP supports 54 services now. Bump the "40+" verbiage in the various READMEs (ex: https://marketplace.visualstudio.com/items?itemName=ms-azuretools.vscode-azure-mcp-server&ssr=false#overview) to 50+.

[alzimmermsft]

Would prefer a more generic term such as Azure MCP Server supercharges your agents with Azure context across numerous Azure services. so that we don't need to repeat this every time we cross some numeric boundry.