tests/xtimer*: select xtimer_no_ztimer_default for tests requiring it

These tests need to be tested on xtimer, and if using ztimer_xtimer_compat
the full api will not be provided, therefore also blacklist BOARDs
that will en up selecting ztimer by default.

tests/xtimer_now32_overflow/Makefile

@@ -1,7 +1,23 @@
 include ../Makefile.tests_common
 
 USEMODULE += xtimer
+USEMODULE += xtimer_no_ztimer_default
 
 DISABLE_MODULE += auto_init_xtimer
 
+# Boards that can't run only on xtimer or that always select ztimer
+BOARD_BLACKLIST += \
+                   feather-nrf52840 \
+                   hamilton \
+                   mulle \
+                   pinetime \
+                   ruuvitag \
+                   stm32f429i-disco \
+                   thingy52 \
+                   waspmote-pro  \
+                   weact-f401cc \
+                   weact-f401ce \
+                   weact-f411ce \
+                   #
+
 include $(RIOTBASE)/Makefile.include

tests/xtimer_now32_overflow/app.config.test

@@ -1,4 +1,5 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_XTIMER=y
+CONFIG_MODULE_XTIMER_NO_ZTIMER_DEFAULT=y
 CONFIG_MODULE_AUTO_INIT_XTIMER=n

tests/xtimer_now64_continuity/Makefile

@@ -2,8 +2,23 @@ include ../Makefile.tests_common
 
 USEMODULE += fmt
 USEMODULE += xtimer
+USEMODULE += xtimer_no_ztimer_default
 
 # This test randomly fails on `native` so disable it from CI
 TEST_ON_CI_BLACKLIST += native
+# Boards that can't run only on xtimer or that always select ztimer
+BOARD_BLACKLIST += \
+                   feather-nrf52840 \
+                   hamilton \
+                   mulle \
+                   pinetime \
+                   ruuvitag \
+                   stm32f429i-disco \
+                   thingy52 \
+                   waspmote-pro  \
+                   weact-f401cc \
+                   weact-f401ce \
+                   weact-f411ce \
+                   #
 
 include $(RIOTBASE)/Makefile.include

tests/xtimer_now64_continuity/app.config.test

@@ -1,4 +1,5 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_XTIMER=y
+CONFIG_MODULE_XTIMER_NO_ZTIMER_DEFAULT=y
 CONFIG_MODULE_FMT=y