Fix issue where only last SAML rule group was applied in Access policy

[Justin-Holmes]

Fixes a bug where SAML rule groups were overwritten so only the last rule was getting applied.

Closes #2018

[github-actions]

changelog detected ✅

[jacobbednarz]

acceptance tests look good, thanks!

TF_ACC=1 go test $(go list ./...) -v -run "^TestAccCloudflareAccessGroupConfig_" -count 1 -parallel 1 -timeout 120m -parallel 1
?   	github.com/cloudflare/terraform-provider-cloudflare	[no test files]
=== RUN   TestAccCloudflareAccessGroupConfig_BasicZone
--- PASS: TestAccCloudflareAccessGroupConfig_BasicZone (19.02s)
=== RUN   TestAccCloudflareAccessGroupConfig_BasicAccount
--- PASS: TestAccCloudflareAccessGroupConfig_BasicAccount (19.01s)
PASS
ok  	github.com/cloudflare/terraform-provider-cloudflare/internal/provider	38.698s

[github-actions]

This functionality has been released in v3.29.0 of the Terraform Cloudflare Provider.

Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!