Backport of docs: Update K8s TGW tutorial to reliably obtain role ID into release/1.15.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #18474 to be assessed for backporting due to the inclusion of the label backport/1.15.

The below text is copied from the body of the original PR.

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The grep command used to obtain the ID for the terminating gateway role is not reliable in all scenarios. For example, if there is a similarly named role, the command may return the wrong role ID for the active terminating gateway instance.

This commit updates the command to use jq to obtain the role ID. If multiple roles are found, jq will raise an error informing the user that it cannot reliably determine the role ID.

Description

Testing & Reproduction steps

Links

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• 1673852

[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR

[hc-github-team-consul-core]

🤔 This PR has changes in the website/ directory but does not have a type/docs-cherrypick label. If the changes are for the next version, this can be ignored. If they are updates to current docs, attach the label to auto cherrypick to the stable-website branch after merging.