fix(actions): upgrade golangci/golangci-lint-action from v8 to v9, and add constant for duplicate string

[Gearheads]

What this PR does / why we need it:

This change will upgrade golangci/golangci-lint-action from v8 to v9, because Node20 has reached its end of life, and there is a new version of golangci/golangci-lint-action that now supports Node24. Also, we created a constant StringType to replace the duplicate strings since the lint GitHub action was failing.

For more information on the deprecation of Node20: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes # https://github.com/fidelity/kconnect/actions/runs/26051077384/job/76587529519

Error: api/v1alpha1/configuration_types.go:100:11: string `string` has 9 occurrences, make it a constant (goconst)
			Type: "string",
				  ^
Error: api/v1alpha1/history_types.go:202:11: string `string` has 9 occurrences, make it a constant (goconst)
			Type: "string",
				  ^
2 issues:
* goconst: 2

level=warning msg="The linter 'gomodguard' is deprecated (since v2.12.0) due to: new major version. Replaced by gomodguard_v2."
level=warning msg="Suggested new configuration:\nlinters:\n  enable:\n    - gomodguard_v2\n"

Error: issues found
Ran golangci-lint in 43306ms

This branch can be deleted once it is merged.