RoundTripper should not add the `/clusters/` segment if already present

[itdove]

When dealing with multiple types of clients (controller-runtime, dynamic...) and also with the NewClusterAwareManager, it is easy to make the mistake to call the NewClusterConfig on the config used by the NewClusterAwareManaager.

The result is that the Roundtripper is registered twice and as being called twice the url contains the cluster workspace twice.

Logic must be added in the Roundtripper to avoid to add again the /clusters/ segment if already present.

[stevekuznetsov]

@ncdc looks like this was not actually fixed in #45, right? This is what we hit today.

[ncdc]

Partially fixed. Still has some edge cases

[ncdc]

45 only checks for same cluster name and avoids adding it multiple times. What you & I hit today is 2 different paths.