Restore original OpenSearch namespaces

Restore original OpenSearch namespaces

Though that URL may no longer resolve, the correct XML namespace for
OpenSearch remains http://a9.com/-/spec/opensearch/1.1/ – see [1] and
[2] for some discussion clarifying this.

Similarly, the canonical namespace URL for MozSearch uses HTTP, not
HTTPS, as can be seen when visiting it (via either protocol) [3].

This reverts commit 3b86cf03c162298211da2f57333bcc645123a979.

[1]: https://github.com/dewitt/opensearch/issues/3
[2]: https://groups.google.com/d/msg/opensearch/8ecuX35-lEs/JR_cs0N6k68J
[3]: https://www.mozilla.org/2006/browser/search/

Bug: T196643
Change-Id: I8d14660550a5c67cefc421a334502963bfd6ed3c