chore: delete unused code

[sofisl]

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Fixes #<issue_number_goes_here> 🦕

[snippet-bot]

Here is the summary of changes.

You are about to delete 13 region tags.

• samples/generated/v1/reachability_service.create_connectivity_test.js:24, tag networkmanagement_v1_generated_ReachabilityService_CreateConnectivityTest_async
• samples/generated/v1/reachability_service.delete_connectivity_test.js:24, tag networkmanagement_v1_generated_ReachabilityService_DeleteConnectivityTest_async
• samples/generated/v1/reachability_service.get_connectivity_test.js:24, tag networkmanagement_v1_generated_ReachabilityService_GetConnectivityTest_async
• samples/generated/v1/reachability_service.list_connectivity_tests.js:24, tag networkmanagement_v1_generated_ReachabilityService_ListConnectivityTests_async
• samples/generated/v1/reachability_service.rerun_connectivity_test.js:24, tag networkmanagement_v1_generated_ReachabilityService_RerunConnectivityTest_async
• samples/generated/v1/reachability_service.update_connectivity_test.js:24, tag networkmanagement_v1_generated_ReachabilityService_UpdateConnectivityTest_async
• samples/generated/v1beta1/reachability_service.create_connectivity_test.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_CreateConnectivityTest_async
• samples/generated/v1beta1/reachability_service.delete_connectivity_test.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_DeleteConnectivityTest_async
• samples/generated/v1beta1/reachability_service.get_connectivity_test.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_GetConnectivityTest_async
• samples/generated/v1beta1/reachability_service.list_connectivity_tests.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_ListConnectivityTests_async
• samples/generated/v1beta1/reachability_service.rerun_connectivity_test.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_RerunConnectivityTest_async
• samples/generated/v1beta1/reachability_service.update_connectivity_test.js:24, tag networkmanagement_v1beta1_generated_ReachabilityService_UpdateConnectivityTest_async
• samples/quickstart.js:17, tag nodejs_network_management_quickstart

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[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .kokoro/.gitattributes - .kokoro files are templated and should be updated in synthtool
• .kokoro/common.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node12/common.cfg - .kokoro files are templated and should be updated in synthtool
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• .kokoro/continuous/node12/samples-test.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/continuous/node12/system-test.cfg - .kokoro files are templated and should be updated in synthtool
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• .kokoro/docs.sh - .kokoro files are templated and should be updated in synthtool
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• .kokoro/presubmit/node12/test.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/publish.sh - .kokoro files are templated and should be updated in synthtool
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• .kokoro/release/docs.cfg - .kokoro files are templated and should be updated in synthtool
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• .kokoro/release/publish.cfg - .kokoro files are templated and should be updated in synthtool
• .kokoro/samples-test.sh - .kokoro files are templated and should be updated in synthtool
• .kokoro/system-test.sh - .kokoro files are templated and should be updated in synthtool
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