fix: resolve Event Grid MI delivery authorization failure

[Vamshi-Microsoft]

Purpose

This pull request makes a series of improvements to the v2/infra/main.bicep file, focusing on code readability, maintainability, and resource provisioning reliability. The main themes are: reformatting long lines for better readability, restructuring resource and variable assignments for clarity, and introducing a more reliable pattern for Event Grid system topic provisioning to avoid deployment race conditions.

Key changes include:

Resource provisioning reliability:

• Introduced a new three-step provisioning pattern for Event Grid system topics to ensure the system-assigned managed identity is available before role assignment and event subscription creation. This prevents deployment errors caused by role assignment propagation delays.

Readability and maintainability improvements:

• Reformatted long inline expressions and object initializations (such as conditional assignments and array/object definitions) to use multi-line, indented blocks for improved readability throughout the file. This includes variable assignments, module parameters, and environment variable definitions. [1] [2] [3] [4] [5] [6] [7] [8] [9]

• Reformatted all roleDefinitionId assignments in resource role assignments to use multi-line calls to subscriptionResourceId, improving consistency and making the code easier to scan and modify. [1] [2] [3] [4] [5] [6] [7] [8] [9]

Environment variable and configuration improvements:

• Updated environment variable definitions for container apps and function apps to use multi-line object syntax for clarity, and standardized the Application Insights connection string variable name for backend container apps to match host expectations. [1] [2] [3]

These changes collectively improve the reliability of infrastructure deployments and make the codebase easier to read and maintain.

Does this introduce a breaking change?

• Yes
• No

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