[Eng] Update regex to match submodule x.autorest case insensitively

[VeryEarly]

Description

powershell -match operator is case insensitive by default : https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_comparison_operators?view=powershell-7.5#common-features

to use case-sensitive match, use operator -cmatch`

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • Update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

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[Copilot]

Pull Request Overview

This PR refines the submodule lookup in AdaptAutorestModule.ps1 to only select Autorest submodules (case‐insensitive by default in PowerShell).

• Changed the -match regex from a generic \. suffix to specifically \.Autorest
• Limits directory selection to Autorest extensions only

[Copilot]

The regex isn't anchored and could match unintended names (e.g., ${subModuleNameTrimmed}.Autorestdir). Consider anchoring the pattern with start/end markers: ^${subModuleNameTrimmed}\.Autorest$.

Suggested change

	$subModuleName = Get-ChildItem -Path $moduleRootPath -Directory | Where-Object { $_.Name -match "${subModuleNameTrimmed}\.Autorest" } | ForEach-Object { $_.Name }
	$subModuleName = Get-ChildItem -Path $moduleRootPath -Directory | Where-Object { $_.Name -match "^${subModuleNameTrimmed}\.Autorest$" } | ForEach-Object { $_.Name }

[VeryEarly]

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