tests: prettier subprocess output in test log (#5485)

Clean subprocess output so that:
- one line of output is just one line without a linebreak
    - like shells handle `echo subshell says: $(echo foo)`
- multiple lines are indented like other pytest output
- error output is dedented and then indented to be like other pytest
output

Minor readability changes remove friction.

test_runner/fixtures/neon_fixtures.py

@@ -1085,15 +1085,32 @@ class AbstractNeonCli(abc.ABC):
             stderr=subprocess.PIPE,
             timeout=timeout,
         )
+
+        indent = "  "
         if not res.returncode:
-            log.info(f"Run {res.args} success: {res.stdout}")
+            stripped = res.stdout.strip()
+            lines = stripped.splitlines()
+            if len(lines) < 2:
+                log.debug(f"Run {res.args} success: {stripped}")
+            else:
+                log.debug("Run %s success:\n%s" % (res.args, textwrap.indent(stripped, indent)))
         elif check_return_code:
             # this way command output will be in recorded and shown in CI in failure message
-            msg = f"""\
-            Run {res.args} failed:
-              stdout: {res.stdout}
-              stderr: {res.stderr}
+            indent = indent * 2
+            msg = textwrap.dedent(
+                """\
+            Run %s failed:
+              stdout:
+            %s
+              stderr:
+            %s
             """
+            )
+            msg = msg % (
+                res.args,
+                textwrap.indent(res.stdout.strip(), indent),
+                textwrap.indent(res.stderr.strip(), indent),
+            )
             log.info(msg)
             raise RuntimeError(msg) from subprocess.CalledProcessError(
                 res.returncode, res.args, res.stdout, res.stderr