fix(tests): smaller distro version string check

Because patch versions of the distro we use
can change with rootfs updates, it is better
to search only for major and minor versions.

Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>

tests/integration_tests/functional/test_kernel_cmdline.py

@@ -29,4 +29,4 @@ def test_init_params(test_microvm_with_api):
     serial = Serial(vm)
     serial.open()
     # If the string does not show up, the test will fail.
-    serial.rx(token="Ubuntu 22.04.2 LTS")
+    serial.rx(token="Ubuntu 22.04")