Fix bwc tests by configuring admin client

[cwperks]

Description

Both the admin client and normal client in the BWC tests are configured with the same username and password for basic auth. Typically, these are supposed to be differentiated as:

• adminClient configured with admin cert for super user access (i.e. test setup and test cleanup)
• normal client for doing actions as a user when testing with security

Check List

• New functionality includes testing
• New functionality has been documented
• New Roles/Permissions have a corresponding security dashboards plugin PR
• API changes companion pull request created
• Commits are signed per the DCO using --signoff

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