Place template annotation on a separate line - #53731

Rails 8.1 added a newline to compiled ERB output (rails/rails#53731), and
ViewComponent compensates with a lineno of -1 so backtraces point at the
right line. That newline lives inside the `<!-- BEGIN ... -->` annotation,
which Rails only prepends when `annotate_rendered_view_with_filenames` is
enabled *and* the template's format is HTML.

Compensating for every ERB template shifted backtraces by one line for
non-HTML templates (`.text.erb`, `.css.erb`) and for every ERB template
when annotations are disabled, such as in production. When coverage was
running, the same mismatch made `strip_annotation_line?` drop everything
up to the first `;` of a preamble that was never emitted, so non-HTML
templates rendered empty.

Move the annotation conditions into `erb_newline_compensation_needed?` on
`Template` so every call site fires exactly when Rails emits the
annotation. The negative lineno is still avoided under coverage
(bugs.ruby-lang.org/issues/19363).

`Template::Inline` had the same off-by-one, and decided the compensation
when the component class was defined rather than when it compiled. It now
shares the predicate and resolves it at compile time, matching
`Template::File`.

Also add the missing `ensure` to the `without_template_annotations` test
helper, so an exception escaping the block no longer leaves annotations
disabled for the rest of the process.