Use Conjur CLI v8.0

[szh]

Desired Outcome

Update scripts to use Conjur CLI v8.0.

Implemented Changes

• Updated 2_prepare_docker_images.sh script to use version 8 of the Conjur CLI image.
• Update CLI commands to use new syntax
• Add new test-curl pod to test master readiness since the new cli container doesn't contain curl
• Remove support for Conjur v4 in all scripts

Connected Issue/Story

CyberArk internal issue ID: ONYX-33379

Changelog

• The CHANGELOG has been updated, or
• This PR does not include user-facing changes and doesn't require a
  CHANGELOG update

Test coverage

• This PR includes new unit and integration tests to go with the code
  changes, or
• The changes in this PR do not require tests

Documentation

• Docs (e.g. READMEs) were updated in this PR
• A follow-up issue to update official docs has been filed here: [insert issue ID]
• This PR does not require updating any documentation

Behavior

• This PR changes product behavior and has been reviewed by a PO, or
• These changes are part of a larger initiative that will be reviewed later, or
• No behavior was changed with this PR

Security

• Security architect has reviewed the changes in this PR,
• These changes are part of a larger initiative with a separate security review, or
• There are no security aspects to these changes

[gl-johnson]

LGTM - but I wonder if we should prepare updates to conjur-authn-k8s-client and secrets-provider-for-k8s scripts before merging. I believe they point to the main branch of this repo for dev environments and e2e tests and still use the old CLI syntax.

[szh]

cyberark/secrets-provider-for-k8s#505 is ready

[szh]

cyberark/conjur-authn-k8s-client#505 is mostly ready. Still trying to debug a failure in the Jenkins E2E test.

[szh]

OK, those are ready now which should unblock this. Can you please approve @gl-johnson?