Inflate ENR inflation syncronously

ENR inflation is happening on the background thread and sometimes it takes than 1 sec and it causes a test failure.

This CL inflates ENR on main in the test scope.

Bug: 355093232
Change-Id: Ic8b5b808d6cd8b37e2d0df2aff7859aae1d037c2
Test: Presubmit
Flag: TEST_ONLY