* build: remove unused scripts

* disable owlbot

---------

Co-authored-by: ohmayr <omairnaveed@ymail.com>

Without this PR, tests fail because warnings are treated as errors. See
https://github.com/googleapis/proto-plus-python/issues/547 for follow up
work related to the warning.

```
________________________________________________________________________________________________________________________ test_serialize_to_dict_float_precision __________________________________________________________________________________________________________________________

    def test_serialize_to_dict_float_precision():
        class Squid(proto.Message):
            mass_kg = proto.Field(proto.FLOAT, number=1)
    
        s = Squid(mass_kg=3.14159265)
    
>       s_dict = Squid.to_dict(s, float_precision=3)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/test_message.py:336: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
proto/message.py:610: in to_dict
    return MessageToDict(
.nox/unit-3-13-implementation-upb/lib/python3.13/site-packages/google/protobuf/json_format.py:158: in MessageToDict
    printer = _Printer(
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <google.protobuf.json_format._Printer object at 0x7fb6d1f15940>, preserving_proto_field_name = True, use_integers_for_enums = True, descriptor_pool = None, float_precision = 3, always_print_fields_with_no_presence = True

    def __init__(
        self,
        preserving_proto_field_name=False,
        use_integers_for_enums=False,
        descriptor_pool=None,
        float_precision=None,
        always_print_fields_with_no_presence=False,
    ):
      self.always_print_fields_with_no_presence = (
          always_print_fields_with_no_presence
      )
      self.preserving_proto_field_name = preserving_proto_field_name
      self.use_integers_for_enums = use_integers_for_enums
      self.descriptor_pool = descriptor_pool
      if float_precision:
>       warnings.warn(
            'float_precision option is deprecated for json_format. '
            'This will turn into error in 7.34.0, please remove it '
            'before that.'
        )
E       UserWarning: float_precision option is deprecated for json_format. This will turn into error in 7.34.0, please remove it before that.

.nox/unit-3-13-implementation-upb/lib/python3.13/site-packages/google/protobuf/json_format.py:195: UserWarning
```

Towards googleapis/librarian#2451

Towards b/375664027

feat: update image to
us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:d7caef319a25d618e20ba798b103434700bfd80015f525802d87621ca2528c90

This PR was created using the following command

```
partheniou@partheniou-vm-3:~/git/proto-plus-python$ librarian update-image -push
...
time=2025-12-12T18:05:15.002Z level=INFO msg="successfully pushed changes" refSpec=+refs/heads/librarian-20251212T180513Z:refs/heads/librarian-20251212T180513Z
time=2025-12-12T18:05:15.002Z level=INFO msg="creating PR" branch=librarian-20251212T180513Z base=main title="chore: librarian update image pull request: 20251212T180513Z"
time=2025-12-12T18:05:16.170Z level=INFO msg="pr created" url=#554
time=2025-12-12T18:05:16.170Z level=INFO msg="labels added to issue" number=554 labels=[]
```

PR created by the Librarian CLI to initialize a release. Merging this PR
will auto trigger a release.

Librarian Version: v0.7.0
Language Image:
us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:d7caef319a25d618e20ba798b103434700bfd80015f525802d87621ca2528c90
<details><summary>proto-plus: 1.27.0</summary>

##
[1.27.0](v1.26.1...v1.27.0)
(2025-12-12)

### Features

* Add classifier for Python 3.14 (#544)
([d9f4151](d9f41512))

</details>