tests/sys/conn_can: rework blacklisted boards

Several boards have been removed from the exclusion list to reassess
their compatibility. This updates test coverage while keeping only truly
incompatible boards excluded.

Signed-off-by: Gilles DOFFE <gilles.doffe@rtone.fr>

tests/sys/conn_can/Makefile.ci

@@ -1,25 +1,3 @@
 BOARD_INSUFFICIENT_MEMORY := \
-    airfy-beacon \
-    calliope-mini \
-    i-nucleo-lrwan1 \
-    im880b \
-    microbit \
-    nrf51dongle \
-    nucleo-f030r8 \
-    nucleo-f031k6 \
-    nucleo-f042k6 \
-    nucleo-f070rb \
-    nucleo-f072rb \
-    nucleo-f302r8 \
-    nucleo-f303k8 \
-    nucleo-f303re \
-    nucleo-f334r8 \
-    nucleo-l031k6 \
-    nucleo-l053r8 \
-    saml10-xpro \
-    saml11-xpro \
-    stm32f030f4-demo \
-    stm32f0discovery \
-    stm32l0538-disco \
-    yunjia-nrf51822 \
+    olimexino-stm32 \
     #