ui: use sys.stdout and sys.stderr all the time (#5991)

We used to allow changing default output and error stream
but that was problematic for the testing. Now it just uses
sys, so capsys should work for the testing.
The proper way to change sys.stdout and sys.stderr is
by using 'redirect_stdout' now.

dvc/ui/__init__.py

@@ -11,6 +11,8 @@ from typing import (
     Union,
 )
 
+from funcy import cached_property
+
 from dvc.progress import Tqdm
 from dvc.utils import colorize
 
@@ -33,25 +35,11 @@ class Formatter:
 
 class Console:
     def __init__(
-        self,
-        formatter: Formatter = None,
-        output: TextIO = None,
-        error: TextIO = None,
-        enable: bool = False,
+        self, formatter: Formatter = None, enable: bool = False,
     ) -> None:
-        self._output: Optional[TextIO] = output
-        self._error: Optional[TextIO] = error
         self.formatter: Formatter = formatter or Formatter()
         self._enabled: bool = enable
 
-    @property
-    def output(self) -> TextIO:
-        return self._output or sys.stdout
-
-    @property
-    def error_output(self) -> TextIO:
-        return self._error or sys.stderr
-
     def enable(self) -> None:
         self._enabled = True
 
@@ -77,7 +65,7 @@ class Console:
             style=style,
             sep=sep,
             end=end,
-            file=self.error_output,
+            file=sys.stderr,
             flush=flush,
         )
 
@@ -94,12 +82,12 @@ class Console:
         if not self._enabled and not force:
             return
 
-        file = file or self.output
+        file = file or sys.stdout
         values = (self.formatter.format(obj, style=style) for obj in objects)
         return print(*values, sep=sep, end=end, file=file, flush=flush)
 
-    def progress(self, *args, **kwargs) -> Tqdm:
-        kwargs.setdefault("file", self.error_output)
+    @staticmethod
+    def progress(*args, **kwargs) -> Tqdm:
         return Tqdm(*args, **kwargs)
 
     def prompt(
@@ -137,15 +125,12 @@ class Console:
             return False
         return answer.startswith("y")
 
-    @property
+    @cached_property
     def rich_console(self):
         """rich_console is only set to stdout for now."""
         from rich import console
 
-        # FIXME: Getting IO Operation on closed file error
-        #  when testing with capsys, therefore we are creating
-        #  one instance each time as a temporary workaround.
-        return console.Console(file=self.output)
+        return console.Console()
 
     def table(
         self,