Add OWNERS to euicc coretests directory

This directory previously relied on transitive owners through
core/tests/coretests, which was not granular enough. Adding the OWNERS
of the code directory under test.

Test: Adding owners file
Bug: 295006271
Change-Id: I360fc5c6681bd9ec4f0c8c29a32976aaaaef7c3a
diff --git a/core/tests/coretests/src/android/service/euicc/OWNERS b/core/tests/coretests/src/android/service/euicc/OWNERS
new file mode 100644
index 0000000..41fc56b4
--- /dev/null
+++ b/core/tests/coretests/src/android/service/euicc/OWNERS
@@ -0,0 +1 @@
+include platform/frameworks/base:/telephony/java/android/service/euicc/OWNERS