fix google_access_context_manager_service_perimeters permadiff

[Charlesleonius]

Implement custom flatten for google_access_context_manager_service_perimeters as ordering my change server side which can cause a permadiff.

Permadiff is causing tests to fail consistently: hashicorp/terraform-provider-google#17370

accesscontextmanager: Implement custom flatten for google_access_context_manager_service_perimeters as ordering my change server side which can cause a permadiff.

[github-actions]

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 2 files changed, 26 insertions(+), 13 deletions(-))
google-beta provider: Diff ( 2 files changed, 26 insertions(+), 13 deletions(-))

[modular-magician]

Tests analytics

Total tests: 4
Passed tests: 1
Skipped tests: 3
Affected tests: 0

Click here to see the affected service packages

• accesscontextmanager

$\textcolor{green}{\textsf{All tests passed!}}$
View the build log

[github-actions]

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[github-actions]

@GoogleCloudPlatform/terraform-team @BBBmau This PR has been waiting for review for 1 week. Please take a look! Use the label disable-review-reminders to disable these notifications.