scripts/coverage.py: s/exit/sys.exit/

the former is supposed to be used in "the interactive interpreter
shell and should not be used in programs.". this function
prints out its argument, and the exit code is 1. so just
print the error message using sys.exit()

see also
https://docs.python.org/3/library/sys.html#sys.exit and
https://docs.python.org/3/library/constants.html#exit

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

scripts/coverage.py

@@ -134,8 +134,7 @@ def generate_coverage_report(path="build/coverage/test", name="tests", input_fil
         maybe_print(f"Found {len(profraw_files)} input files")
 
     if not profraw_files:
-        print("Error: couldn't find any raw profiling data files, can't generate coverage report")
-        exit(1)
+        sys.exit("Error: couldn't find any raw profiling data files, can't generate coverage report")
 
     profdata_path = os.path.join(path, f"{name}.profdata")