Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Remove some useless code
**What this PR does / why we need it**:
code optimization,remove some useless code.
**Release note**:
```release-note
NONE
```
In bringing back Clayton's PR piece-by-piece this was almost as easy to
implement as his version, and is much more like what I think we should be
doing.
Specifically, any time which defines a .DeepCopy() method will have that method
called preferentially. Otherwise we generate our own functions for
deep-copying. This affected exactly one type - resource.Quantity. In applying
this heuristic, several places in the generated code were simplified.
To achieve this I had to convert types.Type.Methods from a slice to a map,
which seems correct anyway (to do by-name lookups).
His PR cam during the middle of this development cycle, and it was easier to
burn it down and recreate it than try to patch it into an existing series and
re-test every assumption. This behavior will be re-introduced in subsequent
commits.
Automatic merge from submit-queue
Resource quantity must support leading and trailing whitespace in JSON for back-compat
For backwards compatibility reasons, we must continue to support leading or trailing whitespace on Quantity values when deserialized from JSON. We must also support numbers serialized into yaml (`cpu: 1`) and JSON (`"cpu": 1`)
Fixes#26898
Instead of saving bytes, save a string, which makes String() faster
and does not unduly penalize marshal. During parse, save the string
if it is in canonical form.
Provides fast transformations of int64 scaled values with overflow to
inf.Dec as needed. Attempts to reduce allocations and expensive
operations in the critical path.
Alters the public signature of Quantity to encourage more efficient use
