tests: canbus: isotp: conformance: skip stmin test on low tick Hz

The CAN ISO-TP conformance test expects to receive a frame within STmin
(5 msec) + upper tolerance (5msec) = 10msec. The expectation fails when
CONFIG_SYS_CLOCK_TICKS_PER_SEC is too low.

Skip the STmin test case to allow the test suite to succeed on non-tickless
and emulation platforms, where CONFIG_SYS_CLOCK_TICKS_PER_SEC defaults to
100. Enable the tests for native_posix and native_posix_64.

Fixes: #54254

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>