ICU-22646 Update collation test for Latvian locale

This test is also relevant to issues ICU-12765 ICU-13508 ICU-20532

Author: Mazurs

icu4c/source/test/testdata/collationtest.txt

@@ -1479,13 +1479,21 @@
 # Latvian sort order.
 @ locale lv
 * compare
+< az
+< ā
+< b
 < cz
 < č
 < d
+< ez
+< ē
+< f
 < gz
 < ģ
 < h
 < iz
+< y
+< ī
 < j
 < kz
 < ķ
@@ -1496,12 +1504,18 @@
 < nz
 < ņ
 < o
+< oz
+< ō
+< p
 < rz
 < ŗ
 < s
 < sz
 < š
 < t
+< uz
+< ū
+< v
 < zz
 < ž