[INLONG-10806][SDK] Optimize python dataproxy sdk build script

[yfsn666]

Fixes #10806

Motivation

Optimize the python dataproxy sdk build script with the following optimizations:

• Enable user to customize the dynamic repository directory in the build script process for the convenience of virtual environment users.
• The pybind11 folder is not deleted at the end of the build, the build process automatically detects if there is a compiled Pybind, and if there is, the Pybind download and build steps will be skipped.
• Do not build dataproxy-cpp-sdk in the python sdk build script, to avoid some potential problems, in the build process to automatically detect whether the c++ sdk has been compiled. If not compiled, it will provide the compilation commands to guide the user to compile the c++ sdk.
• Remove Pybind test step for faster build.

Modifications

Modify the python sdk build script and the correspoding README.

Verifying this change

(Please pick either of the following options)

• This change is a trivial rework/code cleanup without any test coverage.

• This change is already covered by existing tests, such as:
  (please describe tests)

• This change added tests and can be verified as follows:

  (example:)

  • Added integration tests for end-to-end deployment with large payloads (10MB)
  • Extended integration test for recovery after broker failure

Documentation

• Does this pull request introduce a new feature? no