The read_sdc roundtrip section fails in OpenROAD regression because
the shared test environment leaks clock definitions from other tests
(clk2 period 15 vs 20). Roundtrip coverage is already provided by
sdc_write_roundtrip_full which runs in an isolated context.
Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Jaehyun Kim <jhkim@precisioninno.com>