[Dashboard] Fix the display of task/actor GPU info.

[liuxsh9]

Why are these changes needed?

There is a mismatch between the front-end and back-end variables. Front-end: processes, Back-end: processes_pid. Modify the variable name to resolve this issue.

After:

Related issue number

#46213

Checks

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    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
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• Testing Strategy
  • Unit tests
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  • This PR is not tested :(

[jjyao]

This has been fixed in #46719