sanitize_text_field() leaves extra whitespace when stripping octets

[westi]

If you sanitize out some octets from a string like:

We also %AB remove %ab octets

You get: We also__remove__octets

Instead of : We also_remove_octets

Found this while writing test cases for this based on the report in #11528

[westi]

(In [12503]) Improve sanitize_text_field() some more so that we don't leave extra whitespace after stripping octets. Fixes #11573.

[azaozz]

It's not often that there are octets in these strings. Perhaps we can save a little bit by running the last regex only when needed.

[westi]

That looks like a better idea.

And stripping only spaces the second time round looks like a good idea too.

[westi]

(In [12504]) Only run a second spaces strip if we replaced some octets. Also only replace spaces and we have already removed the other whitespace chars. Fixes #11573 props azaozz.