chore: remove dead engine helper functions (batch 6)

[dsyme]

Removes 5 dead functions and their exclusive tests from engine_helpers.go:

• ExtractAgentIdentifier
• GetHostedToolcachePathSetup
• GetSanitizedPATHExport
• GetToolBinsSetup
• GetToolBinsEnvArg

Also removes 8 corresponding test functions from engine_helpers_test.go.

All kept tests pass. Part of the ongoing dead code removal series.

[Copilot]

Pull request overview

Removes previously introduced (now unused) workflow helper functions and their tests as part of the dead-code cleanup series.

Changes:

• Removed several unused validation helpers (and associated tests) from validation_helpers*.
• Removed unused map helper utilities from map_helpers.go.
• Removed unused engine helper utilities (and associated tests) from engine_helpers*.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/workflow/validation_helpers_test.go	Deletes tests for removed validation/map helper utilities.
pkg/workflow/validation_helpers.go	Removes unused exported validation helpers and cleans related imports/docs list.
pkg/workflow/map_helpers.go	Removes unused map helper utilities and cleans related imports/docs list.
pkg/workflow/engine_helpers_test.go	Deletes tests for removed engine helper utilities.
pkg/workflow/engine_helpers.go	Removes unused engine helper utilities.

Comments suppressed due to low confidence (2)

pkg/workflow/engine_helpers.go:273

• This comment references GetHostedToolcachePathSetup(), but that function has been removed in this PR. Update the documentation here to avoid pointing readers to a non-existent helper (e.g., describe the behavior directly or reference the current PATH-setup mechanism).

// GetNpmBinPathSetup returns a simple shell command that adds hostedtoolcache bin directories
// to PATH. This is specifically for npm-installed CLIs (like Claude and Codex) that need
// to find their binaries installed via `npm install -g`.
//
// Unlike GetHostedToolcachePathSetup(), this does NOT use GH_AW_TOOL_BINS because AWF's
// native chroot mode already handles tool-specific paths (GOROOT, JAVA_HOME, etc.) via

pkg/workflow/validation_helpers_test.go:316

• The PR title/description says this change removes dead functions/tests from engine_helpers.go, but this PR also removes validation/map helper functions and a large block of tests in validation_helpers_test.go. Please update the PR description (or split the change) so the scope matches the actual diff.

// TestDirExists tests the fileutil.DirExists helper function
func TestDirExists(t *testing.T) {
	t.Run("empty path returns false", func(t *testing.T) {
		result := fileutil.DirExists("")

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[Copilot]

The file-level docs still describe helpers like string validation and list membership, but those helpers were removed in this PR. Please update this header section so it accurately reflects the remaining exported/available helpers in this file.

See below for a potential fix:

// such as integer range validation, mount string format validation, list formatting,
// and target repository slug validation. These utilities are used across multiple
// workflow configuration validation functions.
//
// # Available Helper Functions
//
//   - validateIntRange() - Validates that an integer value is within a specified range
//   - validateMountStringFormat() - Parses and validates a "source:destination:mode" mount string
//   - formatList() - Formats a slice of strings as a human-readable, comma-separated list
//   - validateTargetRepoSlug() - Validates that a target-repo slug is not the wildcard "*"