Remove `-custom-job` suffix from display names

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**Is your feature request related to a problem? Please describe.**
When creating a `CustomPythonPackageTrainingJob`, I specify the display name:

`job = aiplatform.CustomPythonPackageTrainingJob(display_name='my-job', ...)`

but after calling `job.run(...)` (without specifying a `model_display_name` which is apparently no longer supported in `1.36.4`?), while the `Training Pipelines` tab shows the desired display name, the `Custom Jobs` tab shows that each job has `-custom-job` appended to the display name (i.e. `my-job-custom-job`). This display name is then used in other parts of the codebase, e.g. experiment tracking and Tensorboard.

**Describe the solution you'd like**
I would like to specify the display name of the custom job myself. Or simply use the same display name without appending `-custom-job` to it.
**Describe alternatives you've considered**
n/a
**Additional context**
Screenshot of undesired custom job display name:

从 CustomPythonPackageTrainingJob.run 开始，issue 将其标识为创建 custom job 的入口点，并跟踪其显示名称的生成方式。比较 Training Pipelines 和 Custom Jobs 的名称，然后检查 experiment tracking 和 Tensorboard 如何使用该名称。保留请求的显示名称且不带 -custom-job 后缀即表示完成。

由索引模型根据 Issue 内容生成。