Adjust tests to work with secure cluster

[Jakob3xD]

Description

• Update workflow action versions
• Move functions from opensearchapi/internal/test to internal/test
• Adjust integration test to work with secure opensearch
• adjust golangci-lint config for internal/ folder
• add missing merge_id field for indices segement request
• change custom_foldername field to pointer as it can be null
• skip render search template test with security due to issue

Issues Resolved

List any issues this PR will resolve, e.g. Closes [...].

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 57.26%. Comparing base (5631d3c) to head (88e2761).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #488 +/- ## ======================================= Coverage 57.26% 57.26% ======================================= Files 315 315 Lines 9823 9823 ======================================= Hits 5625 5625 Misses 2904 2904 Partials 1294 1294 ``` | [Flag](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) | Coverage Δ | | |---|---|---| | [integration](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) | `50.80% <ø> (ø)` | | | [unit](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) | `12.84% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project) | Coverage Δ | | |---|---|---| | [opensearchapi/api\_cat-indices.go](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-b3BlbnNlYXJjaGFwaS9hcGlfY2F0LWluZGljZXMuZ28=) | `100.00% <ø> (ø)` | | | [opensearchapi/api\_cluster-stats.go](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-b3BlbnNlYXJjaGFwaS9hcGlfY2x1c3Rlci1zdGF0cy5nbw==) | `100.00% <ø> (ø)` | | | [opensearchapi/api\_indices-segments.go](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-b3BlbnNlYXJjaGFwaS9hcGlfaW5kaWNlcy1zZWdtZW50cy5nbw==) | `100.00% <ø> (ø)` | | | [opensearchapi/api\_nodes-info.go](https://app.codecov.io/gh/opensearch-project/opensearch-go/pull/488?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=opensearch-project#diff-b3BlbnNlYXJjaGFwaS9hcGlfbm9kZXMtaW5mby5nbw==) | `100.00% <ø> (ø)` | |

[Jakob3xD]

Should be easier to review this MR commit by commit.

[Jakob3xD]

I think having SECURE_INTEGRATION being referenced as an environment variable in more than one place isn't great.

It is now only referenced in the IsSecure() function. It makes more sense this way.