refactor: replace legacy WaitNext retry loops with thread-safe backoff.Do closures

[Parthtiw710]

PR Description

Description

This PR addresses the technical debt of legacy WaitNext() retry loops in the piped application, resolving the project-wide TODO in pkg/backoff/backoff.go:

// TODO: Find all using of WaitNext and replace by Do to avoid panic.

By migrating all manual WaitNext iterations to pipedservice.NewRetry(N).Do closures, we encapsulate retry states, prevent potential data races/concurrency panics, and standardize error propagation.

Changes

1. Trigger Package (pkg/app/piped/trigger/)

• cache.go: Refactored getLastTriggeredDeployment using backoff.Do and standard pipedservice.NewRetriableErr wrapping. Added type assertion back to the expected *model.ApplicationDeploymentReference return.
• deployment.go: Updated reportMostRecentlyTriggeredDeployment to run inside a safe .Do() closure.

2. Controller Package (pkg/app/piped/controller/)

• controller.go: Migrated getMostRecentlySuccessfulDeployment, cancelDeployment, and reportApplicationDeployingStatus to the safe .Do() pattern.
• planner.go:
  • Refactored reportDeploymentPlanned, reportDeploymentFailed, and reportDeploymentCancelled to use .Do().
  • Fixed a bug in reportDeploymentFailed where ReportDeploymentPlanned was incorrectly called instead of ReportDeploymentCompleted during failure reporting.
• scheduler.go: Migrated reportStageStatus, reportDeploymentStatusChanged, reportDeploymentCompleted, and reportMostRecentlySuccessfulDeployment.

3. Command Package (pkg/app/piped/cmd/piped/)

• piped.go: Refactored sendPipedMeta to use .Do(). Kept the local retry variable to preserve calling telemetry (retry.Calls()) inside warning logs.

4. Platform Provider / Lambda (pkg/app/piped/platformprovider/lambda/ & pkg/app/piped/executor/lambda/)

• client.go: Updated updateFunctionConfiguration to use .Do() loop instead of WaitNext.
• lambda.go: Refactored the build stage publish step to run within a .Do() closure.

---

Verification & Testing

All packages compile cleanly under Go 1.25.0 and all unit tests passed successfully:

go test -v ./pkg/app/piped/controller/...
go test -v ./pkg/app/piped/platformprovider/lambda/...
go test -v ./pkg/app/piped/executor/lambda/...
go test -v ./pkg/app/piped/trigger/...

No remaining WaitNext references exist anywhere in pkg/app/piped:

$ grep -rn "WaitNext" pkg/app/piped/
# No results found