Revert [QA-2495] add: autogen admin svc account pwd (#530)

[emuzykin1]

This reverts commit 72ef9a5.

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Note

Low Risk
Small Terraform-only rollback that removes a generated secret and its Helm values injection; main risk is any deployment still expecting insights-health-check.user.password to be set.

Overview
This PR reverts the prior change that autogenerated an Insights admin/service-account password in Terraform.

It removes the random_password.ins-svc-admin-password resource and stops injecting that value into insights_values under insights-health-check.user.password in both application.tf and azure/application.tf.

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