Remove unneeded TODO comment

[nakabonne]

What this PR does / why we need it:
We settled on letting Piped watch application configs in Git, even unregistered ones as well.

Which issue(s) this PR fixes:

Fixes #2753

Does this PR introduce a user-facing change?:

NONE

[khanhtc1202]

Nice catch
/approve

[pipecd-bot]

This pull request is APPROVED by khanhtc1202.

Approvers can cancel the approval by writing /approve cancel in a comment. Any additional commits also will change this pull request to be not-approved.

[pipecd-bot]

Code coverage for golang is 32.09%. This pull request decreases coverage by -0.02%.

File	Function	Base	Head	Diff
pkg/app/piped/cloudprovider/terraform/terraform.go	WithAdditionalEnvs	--	0.00%	+0.00%
pkg/app/piped/trigger/determiner.go	Determiner.shouldTriggerOnCommit	--	0.00%	+0.00%
pkg/model/application.go	Application.ContainLabels	--	77.78%	+77.78%
pkg/model/deployment.go	Deployment.ContainLabels	--	77.78%	+77.78%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Init	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.SelectWorkspace	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Plan	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Apply	0.00%	0.00%	+0.00%
pkg/app/piped/trigger/determiner.go	Determiner.ShouldTrigger	0.00%	0.00%	+0.00%
pkg/config/deployment.go	PipelineStage.UnmarshalJSON	34.15%	40.24%	+6.10%
pkg/app/api/grpcapi/web_api.go	WebAPI.UpdateApplication	0.00%	0.00%	+0.00%
pkg/app/launcher/cmd/launcher/binary.go	command.GracefulStop	66.67%	100.00%	+33.33%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Version	0.00%	0.00%	+0.00%
pkg/model/application.go	Application.ContainTags	88.89%	--	-88.89%
pkg/model/deployment.go	Deployment.ContainTags	88.89%	--	-88.89%