Fix: Remove inconsistent human readability warning from docker images

[MaheshThakur9152]

What I did

• Removed Warning: Removed the warning message printed to stderr when docker images output is redirected (non-TTY). This involved removing the logic in tree.go and the unused streamRedirected helper function.
• Formatting Polish: Removed a leading newline in list.go (in the "ambiguous argument" hint).
• Context: Previously, the warning message consumed the first line of stderr. After removing the warning, the ambiguous argument error started with an awkward blank line. I removed this leading newline to ensure clean output.

Why I did it

• Inconsistency: docker images was the only list command (unlike docker ps, docker volume ls, etc.) to emit this warning when piped. This change aligns behavior across the CLI.
• Pipeline Stability: The warning interferes with standard command-line pipelines (e.g., docker images | grep ...) and complicates parsing for users who have relied on this behavior for years.
• Cleaner Output: Removing the warning and the redundant newline ensures stderr remains clean and focused on actual errors or hints, rather than noise.

How I verified it

• New Test: Added TestPrintImageTreeNoWarningWhenRedirected in tree_test.go to ensure no warning is emitted on redirection.
• Existing Tests: Updated list-command-ambiguous.golden to match the cleaner output (verified that the leading blank line is gone).
• CI: Verified all unit tests and linters pass in the dev-container environment.

Related Issue

Closes #6749