[quant][graphmode] Test for another type of ops in insert_observer for if (#39380)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39380
Test for inserting observers for if statement for ops that propagate quantization parameters
Test Plan: Imported from OSS
Differential Revision: D21832477
fbshipit-source-id: 6e0b4ce4a89f847af161bb22338525802adb8b41
