Allow parallelization of per instance config deletions by not locking on the IGM

[askubis]

Allow parallelization of per instance config related operations by not locking on the IGM
Fixes b/270736647
follow up to #12829

compute: allow parallelization of `google_compute_per_instance_config` and `google_compute_region_per_instance_config` deletions by not locking on the parent resource, but including instance name.

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

[modular-magician]

Tests analytics

Total tests: 1097
Passed tests: 1022
Skipped tests: 75
Affected tests: 0

Click here to see the affected service packages

• compute

🟢 All tests passed!

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[github-actions]

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[NickElliot]

LGTM!