meson: skip symbol analysis when tests are disabled or build type is not dev (#44322)

The libshared-unused-symbols test references every executable, including
tests and fuzzers whose build_by_default is false. Meson 1.3 adds test
prerequisites to Ninja's all target, so registering this test pulls
those executables into a build configured even if -Dtests=false.

The resulting executables fail to link because src/shared/tests.c is
excluded from libsystemd-shared when tests are disabled.

Follow-up for 3f0fc93219

(cherry picked from commit dac6eb0a24)
(cherry picked from commit d3ccae621e)

meson.build

@@ -2685,17 +2685,19 @@ if spatch.found()
         endforeach
 endif
 
-symbol_analysis_exes = []
-foreach name, exe : executables_by_name
-        symbol_analysis_exes += exe
-endforeach
+if want_tests != 'false' and conf.get('BUILD_MODE_DEVELOPER') == 1
+        symbol_analysis_exes = []
+        foreach name, exe : executables_by_name
+                symbol_analysis_exes += exe
+        endforeach
 
-test(
-        'libshared-unused-symbols',
-        find_unused_library_symbols_py,
-        suite : 'unused-symbols',
-        args : [libshared, libcore] + nss_targets + pam_targets + symbol_analysis_exes,
-)
+        test(
+                'libshared-unused-symbols',
+                find_unused_library_symbols_py,
+                suite : 'unused-symbols',
+                args : [libshared, libcore] + nss_targets + pam_targets + symbol_analysis_exes,
+        )
+endif
 
 run_target(
         'check-api-docs',