refactor: move codebase to go 1.26

[cgrinds]

https://blog.jetbrains.com/go/2026/02/13/moving-your-codebase-to-go-1-26-with-goland-syntax-updates/

[Copilot]

Pull request overview

This PR upgrades the repository’s Go language version to Go 1.26 and applies the related syntax modernizations across the codebase to reduce boilerplate (notably around error type matching and pointer-to-literal patterns).

Changes:

• Bump go directives to Go 1.26 / 1.26.0 across modules.
• Replace errors.As + temp variables with errors.AsType[T] in multiple call sites.
• Replace “take address of local temp” patterns with new(<expr>) pointer creation where applicable.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/errs/ontap.go	Uses errors.AsType[*RestError] to simplify REST error detection.
pkg/conf/conf_test.go	Simplifies boolean pointer setup with new(true/false) in tests.
pkg/conf/conf.go	Uses new(logSet.GetAllChildNamesS()) instead of local var + address.
pkg/api/ontapi/zapi/client.go	Refactors HarvestError detection to errors.AsType.
mcp/go.mod	Updates module Go version to 1.26.
integration/test/promtool_metrics_test.go	Refactors ExitError detection to errors.AsType.
integration/test/copy_logs_test.go	Refactors ExitError detection to errors.AsType.
integration/go.mod	Updates module Go version to 1.26.0.
integration/certer/main.go	Refactors OntapError detection to errors.AsType.
go.mod	Updates main module Go version to 1.26.0.
cmd/tools/rest/rest.go	Refactors RestError detection to errors.AsType.
cmd/tools/rest/client.go	Refactors RestError detection to errors.AsType.
cmd/poller/poller.go	Uses new(append(...)) to avoid temp slice variable when updating templates.
cmd/exporters/victoriametrics/victoriametrics.go	Uses new(<expr>) for default pointers and URL pointer creation.
cmd/exporters/influxdb/influxdb.go	Uses new(<expr>) for default pointers and URL pointer creation.
cmd/collectors/storagegrid/rest/client.go	Refactors StorageGridError detection to errors.AsType.
cmd/collectors/power.go	Refactors RestError detection to errors.AsType (with status check).
cmd/collectors/eseries/rest/client.go	Refactors RestError detection to errors.AsType.
cmd/collectors/discovery.go	Refactors HarvestError detection to errors.AsType.
cmd/collectors/cisco/rest/client.go	Refactors HarvestError detection to errors.AsType.

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