fix: fixes a bug for issue 289

[coderGo93]

Description

WIP because couldn't replicate the error with indicated steps but it's probably related because the project id was not set in read and it detects "change" like in issue. There's has been a similar error with acceptance test for import, so I set it and the testacc for import worked

Link to any related issue(s):
#289

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Documentation fix/enhancement

Required Checklist:

• I have signed the MongoDB CLA
• I have read the Terraform contribution guidelines
• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirments
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code

Further comments

[themantissa]

Just tested with repro 1) create project/cluster/maintenance window in Atlas UI 2) import those to terraform with a provider built from this branch 3) do a terraform plan w/ tf that matches imported state. Now it shows no changes, as expected! Thank you!