Use |offset| in QuicReceiveControlStreamTests for easier readability.
Use |offset| in QuicReceiveControlStreamTests for easier readability.

gfe-relnote: n/a, test-only change.
PiperOrigin-RevId: 304392728
Change-Id: I4ea2cf01f021608fbb86d50160c6b7cfd4f456de

google/quiche,google/quiche,google/quiche,google/quiche