Allow ModernisationPlatformGithubActionsRole to delete *.tflock files

[dms1981]

Tracked upstream by #8345.

This PR adds a statement allowing the ModernisationPlatformGithubActionsRole to delete native S3 lock files from the modernisation-platform-terraform-state S3 bucket.

[github-actions]

🦙 MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ REPOSITORY	gitleaks	yes		no	0.65s
✅ REPOSITORY	trivy	yes		no	18.24s
✅ TERRAFORM	terraform-fmt	1		0	0.05s
✅ TERRAFORM	tflint	yes		no	12.16s

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