Remove `source` from AST locations before storing them in the shared heap
Remove `source` from AST locations before storing them in the shared heap

Summary: This results in a 2.9% heap size reduction on a certain codebase without noticeably affecting other performance metrics.

Reviewed By: gabelevi

Differential Revision: D13095655

fbshipit-source-id: ed37acbc30bd12cb93369c1acfb8d6bff7aae9d2

AgentME/flow,gabelevi/flow,gabelevi/flow,mroch/flow,gabelevi/flow,popham/flow,samwgoldman/flow,gabelevi/flow,facebook/flow,facebook/flow,samwgoldman/flow,mroch/flow,mroch/flow,popham/flow,mroch/flow,AgentME/flow,popham/flow,mroch/flow,AgentME/flow,facebook/flow,mroch/flow,samwgoldman/flow,popham/flow,facebook/flow,popham/flow,AgentME/flow,AgentME/flow,gabelevi/flow,facebook/flow,samwgoldman/flow,popham/flow,gabelevi/flow,mroch/flow,facebook/flow,samwgoldman/flow,samwgoldman/flow,gabelevi/flow,popham/flow,facebook/flow,samwgoldman/flow