[sdk] kfp.dsl placeholders not getting replaced at runtime (v2)

[KyleKaminky]

Environment

• KFP version: 2.16.1

• KFP SDK version: 2.13.0

• All dependencies version: N/A

Steps to reproduce

Here is a short code snippet of how our team is trying to use the kfp.dsl placeholders.

with dsl.ExitHandler(exit_handler_op):
    entry_handler_op = entry_handler_comp(
        fpst=fp_params_str,
        esp=explicit_string_params,
        pipeline_job_name=dsl.PIPELINE_JOB_NAME_PLACEHOLDER,
        pipeline_job_resource_name=dsl.PIPELINE_JOB_RESOURCE_NAME_PLACEHOLDER,
        pipeline_job_id=dsl.PIPELINE_JOB_ID_PLACEHOLDER,
        pipeline_task_name=dsl.PIPELINE_TASK_NAME_PLACEHOLDER,
        pipeline_task_id=dsl.PIPELINE_TASK_ID_PLACEHOLDER,
        pipeline_task_executor_output_path=dsl.PIPELINE_TASK_EXECUTOR_OUTPUT_PATH_PLACEHOLDER,
        pipeline_task_executor_input=dsl.PIPELINE_TASK_EXECUTOR_INPUT_PLACEHOLDER,
        pipeline_root=dsl.PIPELINE_ROOT_PLACEHOLDER,
        pipeline_job_create_time_utc=dsl.PIPELINE_JOB_CREATE_TIME_UTC_PLACEHOLDER,
        pipeline_job_schedule_time_utc=dsl.PIPELINE_JOB_SCHEDULE_TIME_UTC_PLACEHOLDER,

But at runtime some of the placeholders are not populated correct, while some are.

Expected result

The placeholders should be populated with correct, expected values.

Materials and Reference

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[shreeharshshinde]

Tried to solve in my branch `fix/placeholder-replacement-13424

The three placeholders were missing from the PLACEHOLDERS dict in
resolve_individual_placeholder() in sdk/python/kfp/local/placeholder_utils.py:

• PIPELINE_JOB_RESOURCE_NAME_PLACEHOLDER → maps to pipeline_resource_name
• PIPELINE_JOB_CREATE_TIME_UTC_PLACEHOLDER → UTC timestamp (ISO 8601)
• PIPELINE_JOB_SCHEDULE_TIME_UTC_PLACEHOLDER → UTC timestamp (ISO 8601)

Tests added for all three. PR: #13426