chore: remove build badges

[suztomo]

Removes old badge references.

b/468377909

[suztomo]

The build failure does not seem to related to the change:

      Built google-cloud-aiplatform @ file:///tmpfs/src/github/python-aiplatform
  × Failed to build `llvmlite==0.36.0`
  ├─▶ The build backend returned an error
  ╰─▶ Call to `setuptools.build_meta:__legacy__.build_wheel` failed (exit
      status: 1)

      [stderr]
      Traceback (most recent call last):
        File "", line 14, in 
          requires = get_requires_for_build({})
        File
      "/root/.cache/uv/builds-v0/.tmphB6hhb/lib/python3.13/site-packages/setuptools/build_meta.py",
      line 331, in get_requires_for_build_wheel
          return self._get_build_requires(config_settings, requirements=[])
                 ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File
      "/root/.cache/uv/builds-v0/.tmphB6hhb/lib/python3.13/site-packages/setuptools/build_meta.py",
      line 301, in _get_build_requires
          self.run_setup()
          ~~~~~~~~~~~~~~^^
        File
      "/root/.cache/uv/builds-v0/.tmphB6hhb/lib/python3.13/site-packages/setuptools/build_meta.py",
      line 512, in run_setup
          super().run_setup(setup_script=setup_script)
          ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File
      "/root/.cache/uv/builds-v0/.tmphB6hhb/lib/python3.13/site-packages/setuptools/build_meta.py",
      line 317, in run_setup
          exec(code, locals())
          ~~~~^^^^^^^^^^^^^^^^
        File "", line 55, in 
        File "", line 52, in _guard_py_ver
      RuntimeError: Cannot install on Python version 3.13.9; only versions
      >=3.6,<3.10 are supported.

      hint: This usually indicates a problem with the package or the build
      environment.
  help: `llvmlite` (v0.36.0) was included because
        `google-cloud-aiplatform[testing]` (v1.132.0) depends on `lit-nlp`
        (v0.4) which depends on `umap-learn` (v0.5.9.post2) which depends on
        `numba` (v0.53.1) which depends on `llvmlite`

nox > Session unit-3.13 failed.