tree-wide: drop flush&check step after table printing

Almost all callers of table_print() specify stdout or NULL (equivalent
to stdout) as the output stream. Simplify things by not requiring the
the stream to be specified.

In almost all cases, the printing of the table is surrounded by normal
printfs() that don't do explicit flushing and for which we don't check
the output stream status. Let's simplify most callers and skip this
step. The reason is not so much to avoid the extra step itself, but
instead to avoid the _handling_ of the potential failure. We generally
only want to print an error message for ENOMEM and other "internal"
errors, so strictly speaking we should filter out the errors from the
stream. By skipping the flush&check step we implicitly do this.

src/shared/format-table.c

@@ -2217,7 +2217,7 @@ int _table_sync_column_widths(size_t column, Table *a, ...) {
         return r;
 }
 
-int table_print(Table *t, FILE *f) {
+int table_print_full(Table *t, FILE *f, bool flush) {
         size_t n_rows, *minimum_width, *maximum_width, display_columns, *requested_width,
                 table_minimum_width, table_maximum_width, table_requested_width, table_effective_width,
                 *width = NULL;
@@ -2637,6 +2637,9 @@ int table_print(Table *t, FILE *f) {
                 } while (more_sublines);
         }
 
+        if (!flush)
+                return 0;
+
         return fflush_and_check(f);
 }
 
@@ -2652,7 +2655,7 @@ int table_format(Table *t, char **ret) {
         if (!f)
                 return -ENOMEM;
 
-        r = table_print(t, f);
+        r = table_print_full(t, f, /* flush= */ true);
         if (r < 0)
                 return r;
 
@@ -3141,7 +3144,7 @@ int table_print_json(Table *t, FILE *f, sd_json_format_flags_t flags) {
         assert(t);
 
         if (!sd_json_format_enabled(flags)) /* If JSON output is turned off, use regular output */
-                return table_print(t, f);
+                return table_print_full(t, f, /* flush= */ true);
 
         if (!f)
                 f = stdout;