test: fix GCC_PREPROCESSOR_DEFINITIONS from TEST/TESTCI to SENTRY_ prefix (#5541)

Author: armcknight

Samples/Shared/Config/ClangPreprocessing.xcconfig

@@ -7,7 +7,7 @@ ENABLE_NS_ASSERTIONS_Release = NO
 ENABLE_NS_ASSERTIONS = $(ENABLE_NS_ASSERTIONS_$(CONFIGURATION))
 
 GCC_PREPROCESSOR_DEFINITIONS_Debug = DEBUG=1 $(inherited)
-GCC_PREPROCESSOR_DEFINITIONS_Test = TEST=1 $(inherited)
-GCC_PREPROCESSOR_DEFINITIONS_TestCI = TESTCI=1 $(inherited)
+GCC_PREPROCESSOR_DEFINITIONS_Test = SENTRY_TEST=1 $(inherited)
+GCC_PREPROCESSOR_DEFINITIONS_TestCI = SENTRY_TESTCI=1 $(inherited)
 GCC_PREPROCESSOR_DEFINITIONS_Release = RELEASE=1 $(inherited)
 GCC_PREPROCESSOR_DEFINITIONS = $(GCC_PREPROCESSOR_DEFINITIONS_$(CONFIGURATION))