fix: treat omitted remote_state_consumer_ids as an empty set during updates

[ctrombley]

Description

This fix PR resolves #2000.

Testing plan

1. Reproduce with a config similar to that provided in Removing remote_state_consumer_ids from a tfe_workspace_settings resource does not actually remove them #2000
2. Ensure that with the fix in place, omitting remote_state_consumer_ids from a config that previously used it clears out the relationships successfully.

[datadog-terraform-cloud-hashicorp]

⚠️ Tests

✨ Fix all issues with Cursor

⚠️ Warnings

🧪 2 Tests failed

TestAccTFEWorkspaceDataSource_remoteStateConsumers from data_source_workspace_test.go     (Fix with Cursor)

Step 1/3 error: After applying this test step, the non-refresh plan was not empty.
stdout:


Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

...

TestAccTFEWorkspaceSettingsRemoteState from resource_tfe_workspace_settings_test.go     (Fix with Cursor)

Step 2/7 error: Error running apply: exit status 1

Error: Provider produced inconsistent result after apply

When applying changes to tfe_workspace_settings.foobar, provider
"provider[\"registry.terraform.io/hashicorp/tfe\"]" produced an unexpected
new value: .overwrites[0].agent_pool: was cty.False, but now cty.True.

This is a bug in the provider, which should be reported in the provider's own
issue tracker.
...

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

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