Legacy syslog bindings code cleanup

[chombium]

Description

With the introduction of mTLS for Syslog Drains we have changed the internal structure of the bindings. In order to enable updating without downtime of the cloud controller, the syslog binding cache and the syslog agent, we have introduced two endpoints for reading the syslog binding in the old and new format. This PR cleans up the code of the legacy syslog bindings and removes the http calls to the old Syslog Binding Cache API endpoint. From now on, only the /v2/binding and /v2/aggregate-bindings API endpoints of the Syslog Binding Cache will be used.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Testing performed?

• Unit tests
• Integration tests
• Acceptance tests

Checklist:

• This PR is being made against the main branch, or relevant version branch
• I have made corresponding changes to the documentation
• I have added testing for my changes

This PR should be merged after merging the changes introduced with the this PR in the Cloud Controller

[mkocher]

Great to see things getting cleaned up. We have some environments that have older syslog-binding-caches that do not speak /v2. We'd like to merge this and then cut a v8 line of loggregator-agent-release.

We'd like to wait a week or two to cut the v8 line so that we can double check that we're not going to pull in a v8 release into places where it shouldn't go. We're also thinking that we'd like to move otel-collector out to its own release, which would also be a breaking change. Are you OK with waiting a little bit and merging this and the otel-collector split in the same release?

[chombium]

Hi, @mkocher thank you very much for the review and the approval.
I know that @acrmp had some doubts about the usage of the original Syslog Binding Cache we (myself, @fhambrec, @Benjamintf1 and @ctlong) have added the new /v2 endpoints when we implemented mutual TLS to transfer certificates to the Syslog Agent and. The other important thing was to avoid downtime during CF update.

I've adjusted only Syslog Agent as that is the only Syslog Binding Cache that I know of. If you have any other internal consumers, take your time to adjust them. There is no rush yo merge this. We still have to wait for the changes in the Cloud Controller to be merged qnd new capi release is cut and added in cf-deployment. Do the needful and we'll create a new release when we're ready.