Because Ztunnel can have Istio semantics baked in, we do not need to encode all this information on the wire.
Instead, an Istio specific field like `ExpectedTLSIdentity: spiffe://foo.bar` can encode the same information, at a fraction of the cost.

In our testing, even the most generous representations give custom types a 10x edge (in size, allocations, and CPU time) over Envoy types.

  // `limitResponse` indicates what to do with requests that can not be executed right now
  optional LimitResponse limitResponse = 2;

  // `lendablePercent` prescribes the fraction of the level's NominalCL that
  // can be borrowed by other priority levels. The value of this
  // field must be between 0 and 100, inclusive, and it defaults to 0.

  // `limitResponse` indicates what to do with requests that can not be executed right now
  optional LimitResponse limitResponse = 2;

  // `lendablePercent` prescribes the fraction of the level's NominalCL that
  // can be borrowed by other priority levels. The value of this
  // field must be between 0 and 100, inclusive, and it defaults to 0.

        gradient ops and avoid an extra gather operation that was in the
        previous gradient implementation.
    *   Added a new session config setting `internal_fragmentation_fraction`,
        which controls when the BFC Allocator needs to split an oversized chunk
        to satisfy an allocation request.
    *   Added `tf.get_current_name_scope()` which returns the current full name

- Apiserver add a new flag --goaway-chance which is the fraction of requests that will be closed gracefully(GOAWAY) to prevent HTTP/2 clients from getting stuck on a single apiserver. 

  // `limitResponse` indicates what to do with requests that can not be executed right now
  optional LimitResponse limitResponse = 2;

  // `lendablePercent` prescribes the fraction of the level's NominalCL that
  // can be borrowed by other priority levels. The value of this
  // field must be between 0 and 100, inclusive, and it defaults to 0.

  // `limitResponse` indicates what to do with requests that can not be executed right now
  optional LimitResponse limitResponse = 2;

  // `lendablePercent` prescribes the fraction of the level's NominalCL that
  // can be borrowed by other priority levels. The value of this
  // field must be between 0 and 100, inclusive, and it defaults to 0.

- Apiserver added a new flag --goaway-chance which is the fraction of requests that will be closed gracefully(GOAWAY) to prevent HTTP/2 clients from getting stuck on a single apiserver. ([#88567](https://github.com/kubernetes/kubernetes/pull/88567), [@answer1991](https://github.com/answer1991)) [SIG API Machinery]...

215B          ; mapped                 ; 0031 2044 0038 #1.1  VULGAR FRACTION ONE EIGHTH
215C          ; mapped                 ; 0033 2044 0038 #1.1  VULGAR FRACTION THREE EIGHTHS
215D          ; mapped                 ; 0035 2044 0038 #1.1  VULGAR FRACTION FIVE EIGHTHS
215E          ; mapped                 ; 0037 2044 0038 #1.1  VULGAR FRACTION SEVEN EIGHTHS

    - `apiserver_flowcontrol_demand_seats_smoothed`: Smoothed seat demands
    - `apiserver_flowcontrol_target_seats`: Seat allocation targets
    - `apiserver_flowcontrol_seat_fair_frac`: Fair fraction of server's concurrency to allocate to each priority level that can use it
    - `apiserver_flowcontrol_current_limit_seats`: current derived number of execution seats available to each priority level