cleanup: move indexers to controller/indexers

[lionelvillard]

No description provided.

[Copilot]

Pull request overview

This PR relocates the VariantAutoscaling field indexer helpers into internal/controller/indexers, updates call sites/imports accordingly, and adjusts related tests and module metadata to reflect the refactor.

Changes:

• Moved indexer utilities into internal/controller/indexers and updated imports/usages across controller/collector and main wiring.
• Added/updated envtest-based tests for the new indexers package and fixed relative paths after the move.
• Applied gofmt/tidy-style cleanup in several tests and dependency files.

Reviewed changes

Copilot reviewed 7 out of 13 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/e2e-openshift/sharegpt_scaleup_test.go	gofmt-style string concatenation cleanup in metric query path building.
test/e2e-openshift/scale_to_zero_test.go	gofmt-style alignment/formatting cleanup.
test/chart/client_only_install_test.go	gofmt-style map literal alignment/formatting cleanup.
internal/engines/saturation/engine.go	Import ordering cleanup.
internal/controller/variantautoscaling_controller.go	Updated import to new indexers package location.
internal/controller/indexers/suite_test.go	Updated envtest CRD/binary relative paths due to new directory depth.
internal/controller/indexers/indexers_test.go	Added envtest coverage for index registration and lookup behavior.
internal/controller/indexers/indexers.go	New indexers package: index registration + lookup helpers keyed by scale target.
internal/collector/source/pod_va_mapper_test.go	Updated import to new indexers package location.
internal/collector/source/pod_va_mapper.go	Updated import to new indexers package location.
cmd/main.go	Updated import and wiring to call indexers.SetupIndexes from new location.
go.mod	Promoted gonum to a direct dependency.
go.sum	Removed old gonum checksums and kept current version entries.