Update ADK doc according to issue #1048 - 7

[adk-bot]

[Feature] Document Application Integration connection_template_override.
The ApplicationIntegrationToolset now has a connection_template_override parameter.

Proposed Change:
In docs/tools/google-cloud-tools.md, update the ApplicationIntegrationToolset section.

Current state:
The documentation for ApplicationIntegrationToolset does not mention this parameter.

Proposed Change:
Add a note about the connection_template_override parameter to the ApplicationIntegrationToolset section.

connector_tool = ApplicationIntegrationToolset(
    project="test-project",
    location="us-central1",
    connection="test-connection",
    connection_template_override="MyExecuteConnection",
)

Reasoning:
This new parameter allows users to override the default connection template, which should be documented.

Reference:

• src/google/adk/tools/application_integration_tool/application_integration_toolset.py