test: PROJECT_FILE macro cannot be used in generated code

test: PROJECT_FILE macro cannot be used in generated code

If the build directory is outside of the source tree, ASSERT_XYZ()
triggers the following warning:
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[20/569] Compiling C object test-hashmap.p/meson-generated_.._src_test_test-hashmap-ordered.c.o
In file included from ../../home/watanabe/git/systemd/src/basic/macro.h:399,
                 from ../../home/watanabe/git/systemd/src/basic/alloc-util.h:10,
                 from src/test/test-hashmap-ordered.c:5:
src/test/test-hashmap-ordered.c: In function ‘test_ordered_hashmap_get’:
../../home/watanabe/git/systemd/src/basic/log.h:216:27: warning: offset ‘32’ outside bounds of constant string [-Warray-bounds=]
  216 |                         ? log_internal(_level, _e, PROJECT_FILE, __LINE__, __func__, __VA_ARGS__) \
      |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../home/watanabe/git/systemd/src/basic/log.h:238:24: note: in expansion of macro ‘log_full_errno_zerook’
  238 |                 (void) log_full_errno_zerook(level, 0, fmt, ##__VA_ARGS__); \
      |                        ^~~~~~~~~~~~~~~~~~~~~
../../home/watanabe/git/systemd/src/basic/log.h:248:28: note: in expansion of macro ‘log_full’
  248 | #define log_error(...)     log_full(LOG_ERR,     __VA_ARGS__)
      |                            ^~~~~~~~
../../home/watanabe/git/systemd/src/shared/tests.h:251:25: note: in expansion of macro ‘log_error’
  251 |                         log_error("%s:%i: Assertion failed: expected \"%s\" to be NULL, but \"%p\" != NULL",    \
      |                         ^~~~~~~~~
src/test/test-hashmap-ordered.c:614:9: note: in expansion of macro ‘ASSERT_NULL’
  614 |         ASSERT_NULL(r);
      |         ^~~~~~~~~~~
===