[FIX] base: do not duplicate spaces for t-foreach

The duplication was used to have a cleaner html page source code by
aligning the <script t-foreach/> for example. However, this behavior
seems difficult to understand and use. Additionally the behavior can be
done with a <t> tag and placing the script inside.

From now on, the space "trick" is only done for <t> tags, so the
template fragment

    <article t-foreach="[0, 1, 2]" t-as="value" t-esc="value"/>
    <t t-foreach="[0, 1, 2]" t-as="value">
        <article t-esc="value"/>
    </t>

renders as

    <article>0</article><article>1</article><article>2</article>
        <article>0</article>
        <article>1</article>
        <article>2</article>

closes odoo/odoo#86695

X-original-commit: 8f817790d3f36455c66647e79df40b7173ac498a
Signed-off-by: Raphael Collet <rco@odoo.com>