Make test data generation reproducible

Specify a fixed timestamp and UUID so that test data generation is
repeatable.

Test: th
Change-Id: I453e9f01059b17625ae70d0cb33878aa604ec993
diff --git a/sample_images/generate_test_erofs_images.sh b/sample_images/generate_test_erofs_images.sh
index a810529..2c69c91 100755
--- a/sample_images/generate_test_erofs_images.sh
+++ b/sample_images/generate_test_erofs_images.sh
@@ -41,4 +41,4 @@
   truncate -s 16M ${fs_root}/dir1/dir2/dir123/chunks_of_zero
 fi
 
-${mkfs} -z $compression_algo ${output_image} ${fs_root}
+${mkfs} -z $compression_algo -T 1656466080 -U BCF5939B-0930-A551-A548-E4BD99E783AC --ignore-mtime ${output_image} ${fs_root}