[3/4] remove get_all_hook_defs from ExecutionPlan, move to callsite
Summary: Continuing the journey of being able to construct an ExecutionPlan without access to a PipelineDefinition, remove this method and have the callsite fetch the steps and use the PipelineDefinition there..
Test Plan: BK
Reviewers: alangenfeld, yuhan
Reviewed By: yuhan
Differential Revision: https://dagster.phacility.com/D6142