Migrated resource compute instance group manager internal test to use transport_tpg

[jcromanu]

… transport_tpg

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compute: migrated `google_compute_instance_group_manager_internal_test` resource  to use direct HTTP rather than a client library

[github-actions]

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 3dba87d:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	3 files changed, 116 insertions(+), 76 deletions(-)
google-beta provider	View Diff	3 files changed, 116 insertions(+), 76 deletions(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
1422	1331	91	0

Affected Service Packages

• compute

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@jcromanu, @NickElliot, @RooBarsic VCR tests complete for 3dba87d!