chore(fixit): remove redundant region tags

[briandorsey]

Removed these tags:
run_tips_global_lazy
run_tips_global_scope
run_service_to_service_auth
run_secure_request
run_secure_request_do
run_system_package_handler
run_system_package_exec

Manually searched docs and confirmed no references remain.

Description

Fixes #

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Checklist

• I have followed Contributing Guidelines from CONTRIBUTING.MD
• Tests pass: go test -v ./.. (see Testing)
• Code formatted: gofmt (see Formatting)
• Vetting pass: go vet (see Formatting)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[snippet-bot]

Here is the summary of changes.

You are about to delete 7 region tags.

• functions/tips/lazy.go:17, tag run_tips_global_lazy
• functions/tips/scope.go:27, tag run_tips_global_scope
• run/authentication/auth.go:19, tag run_service_to_service_auth
• run/markdown-preview/editor/render.go:18, tag run_secure_request
• run/markdown-preview/editor/render.go:72, tag run_secure_request_do
• run/system_package/graphviz.go:57, tag run_system_package_handler
• run/system_package/graphviz.go:95, tag run_system_package_exec

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