various: do not include file names directly in error messages

git grep -l 'Failed to open /'|xargs sed -r -i 's|"Failed to open (/[^ ]+): %m"|"Failed to open %s: %m", "\1"|g'
git grep -l $'Failed to open \'/'|xargs sed -r -i $'s|"Failed to open \'(/[^ ]+)\': %m"|"Failed to open %s: %m", "\\1"|g'
git grep -l "Failed to open /"|xargs sed -r -i $'s|"Failed to open (/[^ ]+), ignoring: %m"|"Failed to open %s, ignoring: %m", "\\1"|g'
+ some manual fixups.

src/sleep/sleep.c

@@ -266,7 +266,7 @@ static int execute(
         /* This file is opened first, so that if we hit an error, we can abort before modifying any state. */
         state_fd = open("/sys/power/state", O_WRONLY|O_CLOEXEC);
         if (state_fd < 0)
-                return log_error_errno(errno, "Failed to open /sys/power/state: %m");
+                return log_error_errno(errno, "Failed to open %s: %m", "/sys/power/state");
 
         if (sleep_needs_mem_sleep(sleep_config, operation)) {
                 r = write_mode("/sys/power/mem_sleep", sleep_config->mem_modes);