Make test 1935 avoid entering jit code before test thread starts

Test 1935 was checking that a method was in OSR code but it was
possible that the JIT actually managed to fully compile the method
before we began executing it, meaning we would be running full JIT
code. This would cause the test to fail. To fix this we changed the
test to leave the JIT disabled until the test method is already
executing.

Test: ./test.py --host -j50
Bug: 77306669
Change-Id: I1d6053b32ef4b1d0fcca39be71cf83a34c7e96ce